Crystalline chromosilicates and process of preparation

ABSTRACT

There are provided crystalline chromosilicates, their methods of preparation, and process uses. A first crystalline chromosilicate comprises a molecular sieve material providing a specific X-ray diffraction pattern and having the following composition in terms of mole ratios of oxides: 
     
         0.9±0.2 [WR.sub.2 O+(1-W)M.sub.2/n O]: Cr.sub.2 O.sub.3 : YSiO.sub.2 : 
    
      ZH 2  O, 
     wherein R is an alkylammonium cation, M is at least one cation having a valence of n, Y is a value within the range of about 4 to about 500, Z is a value within the range of about 0 to about 160, and W is a value that is greater than or equal to 0 and less than or equal to 1. A second crystalline chromosilicate comprises a molecular sieve material providing a specific X-ray diffraction pattern and having the following composition in terms of mole ratios of oxides: 
     
         0.9±0.2 M.sub.2/n O: Cr.sub.2 O.sub.3 : YSiO.sub.2 : ZH.sub.2 O, 
    
     wherein M is at least one cation having a valence of n, Y is within the range of about 4 to about 500, and Z is within the range of about 0 to about 160. The first crystalline chromosilicate is a precursor of the second. 
     There is provided also a process for the conversion of a hydrocarbon stream, which process comprises contacting said stream under hydrocarbon conversion conditions with a catalyst comprising the second crystalline chromosilicate. In addition, there is provided a process for the isomerization of a xylene feed, which process comprises contacting said feed under isomerization conditions with a catalyst comprising the second crystalline chromosilicate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of co-pendingapplication, U.S. Ser. No. 927,843, filed in the United States Patentand Trademark Office on July 25, 1978, and is now abandoned U.S. Ser.No. 927,843 is, in turn, a continuation application of U.S. Ser. No.733,269, which was filed in the United States Patent and TrademarkOffice on Oct. 18, 1976, and is now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to novel crystalline chromosilicates and to theiruse. More particularly, this invention relates to novel chromosilicatecrystalline molecular sieve materials having catalytic properties and tovarious hydrocarbon conversion processes using such crystallinechromosilicates. The field of art can, in part, be found in U.S. PatentClass 423-326, 252-458 and 260-668.

2. Description of the Prior Art

Zeolitic materials, both natural and synthetic, have been demonstratedin the past to have catalytic capabilities for many hydrocarbonprocesses. Certain zeolitic materials are ordered porous crystallinealuminosilicates having a definite structure with large and smallcavities interconnected by channels. The cavities and channelsthroughout the crystalline material are generally uniform in size,allowing certain hydrocarbons to be selectively adsorbed giving one ofthe practical utilities to these materials. Consequently, thesematerials in many instances have come to be classified in the art asmolecular sieves and are utilized, in addition to the adsorptiveselective processes, for certain catalytic properties. The catalyticproperties of these materials are also affected in some instances by thesize of the molecules which are allowed selectively to penetrate thecrystal structure presumably to be contacted with active catalytic siteswithin the ordered structure of these materials.

Generally the term "molecular sieve" includes a wide variety of positiveion containing crystalline materials of both natural and syntheticvarieties. They are generally characterized as crystallinealuminosilicates, although other crystalline materials are included inthe broad definition. The crystalline aluminosilicates are made up ofnetworks of tetrahedra of SiO₄ and AlO₄ moieties in which the siliconand aluminum atoms are cross-linked by the sharing of oxygen atoms. Theelectrovalence of the aluminum atom is balanced by the use of a positiveion, for example, alkali metals or alkaline earth metals.

Prior art developments have resulted in the formation of many syntheticcrystalline materials. Crystalline aluminosilicates are the mostprevalent and, as described in the patent literature and in thepublished journals, are designated by letters or other convenientsymbols. Exemplary of these materials are Zeolite A (U.S. Pat. No.2,882,243), Zeolite X (U.S. Pat. No. 2,882,244), Zeolite Y (U.S. Pat.No. 3,130,007), Zeolite ZSM-5 (U.S. Pat. No. 3,702,886), Zeolite ZSM-11(U.S. Pat. No. 3,709,979), Zeolite ZSM-12 (U.S. Pat. No. 3,832,449), andothers.

Especially relevant art is the above U.S. Pat. No. 3,702,886, claimingthe crystalline aluminosilicate Zeolite ZSM-5 and the method for makingthe same. This patent is limited to the production of a zeolite whereinaluminum or gallium oxides are present in the crystalline structurealong with silicon or germanium oxides. A specific ratio of the latterto the former are reacted to produce a class of zeolites designatedZSM-5 all limited to crystalline alumino- or gallo-silicates orgermanates and having a specified X-ray diffraction pattern. The aboveZSM-11 and ZSM-12 patents are similarly limited to crystalline alumino-or gallo-silicates or germanates also having specified X-ray diffractionpatterns.

Manufacture of the ZSM materials utilizes a mixed base system in whichmaterials such as sodium aluminate and a silica-containing material aremixed together with sodium hydroxide and an organic base, such astetrapropylammonium hydroxide and tetrapropylammonium bromide, underspecified reaction conditions to form the crystalline aluminosilicatematerial having a specific X-ray diffraction pattern.

Other relevant art includes U.S. Pat. Nos. 3,329,480 and 3,329,481,which relate to "zircono-silicates" and "titano-silicates" respectively.

The present invention, however, relates to a novel family of stablesynthetic crystalline materials characterized as chromosilicatesidentified as AMS-1Cr and having a specified X-ray diffraction pattern.The claimed AMS-1Cr crystalline chromosilicates are formed by reacting achromium salt and a silicon-containing material in a basic medium. Theproduct formed contains very little aluminum atoms in its crystallinenetwork.

SUMMARY OF THE INVENTION

The present invention relates to novel synthetic AMS-1Cr crystallinechromosilicates. Such AMS-1Cr crystalline chromosilicate materials havespecified X-ray diffraction patterns, as is shown hereinafter.

Broadly, there is provided a first crystalline chromosilicate whichcomprises a molecular sieve material providing an X-ray diffractionpattern comprising the following X-ray diffraction lines and assignedstrengths:

    ______________________________________                                        Interplanar Spacing  Assigned                                                 d, A                 Strength                                                 ______________________________________                                        11.04 ± 0.2       S                                                        10.04 ± 0.2       S                                                        3.80 ± 0.07       VS                                                       3.74 ± 0.05       M                                                        3.70 ± 0.05       S                                                        3.64 ± 0.05       MS                                                       ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2[WR.sub.2 O+(1-W)M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein R is an alkylammonium cation, M is at least one cation having avalence of n, Y is a value within the range of about 4 to about 500, Zis a value within the range of about 0 to about 160, and W is a valuethat is greater than or equal to 0 and less than or equal to 1.

There is also provided a second crystalline chromosilicate, whichchromosilicate comprises a molecular sieve material providing an X-raydiffraction pattern comprising the following X-ray diffraction lines andassigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

The first crystalline chromosilicate is a precursor of the second.

There is provided a method for preparing a crystalline chromosilicate,which method comprises: (1) preparing a mixture containing an oxide ofsilicon, a compound of chromium, a hydroxide of an alkali metal or analkaline earth metal, an alkylammonium cation or a precursor of analkylammonium cation, and water; (2) maintaining said mixture atsuitable reaction conditions to effect formation of said chromosilicate,said reaction conditions comprising a temperature within the range ofabout 25° C. to about 300° C., a pressure of at least the vapor pressureof water at said temperature, and a reaction time that is sufficient toeffect crystallization to crystals of said chromosilicate; and (3)drying said crystals. This is the method for preparing the firstcrystalline chromosilicate.

The method for preparing the second crystalline chromosilicate comprisesall the steps of the above method followed by the step of activating thecrystals by heat treating the crystals at a temperature within the rangeof about 800° F. (427° C.) to about 1,700° F. (927° C.) in the presenceof a hydrogen-containing atmosphere.

There is provided a process for the conversion of a hydrocarbon stream,which process comprises contacting said stream under hydrocarbonconversion conditions with a catalyst comprising the second crystallinechromosilicate described hereinabove.

There is also provided a process for the catalytic isomerization of axylene feed, which process comprises contacting said feed underisomerization conditions with a catalyst comprising the secondcrystalline chromosilicate described hereinabove.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

The accompanying FIGURE depicts the relationships between threechromosilicate compositions, identified as Composition A (as preparedbut without a high-temperature treatment), Composition B (heat-treatedin an oxygen-containing atmosphere), and Composition C (heat-treated ina hydrogen-containing atmosphere).

DESCRIPTION AND SPECIFIC EMBODIMENTS

The present invention relates to novel synthetic crystalline molecularsieve materials, crystalline chromosilicates. Such crystallinechromosilicate materials, which are identified as AMS-1Crchromosilicates, have particular X-ray diffraction patterns, as areshown in the various tables hereinafter.

Such crystalline chromosilicates can be characterized generally in termsof the mole ratios of oxides as shown in Expression I:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O (I),

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z represents the waterpresent in such material and has a value within the range of 0 to about160, or more.

In another instance, the claimed AMS-1Cr crystalline chromosilicate canbe represented in terms of mole ratios of oxides for the crystallinematerial which has not yet been activated at a high temperature as isshown hereinafter in Expression II:

    0.9±0.2[WR.sub.2 O+[1-W]M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O                                               (II),

wherein R is tetrapropylammonium cation, M is at least one cation havinga valence of n, Y is a value within the range of about 4 to about 500, Zis a value within the range of about 0 to about 160, and W is a valuethat is greater than or equal to 0 and less than or equal to 1.

The original cation, that is M in the above formulations, can bereplaced in accordance with techniques well known in the art, at leastin part by ion exchange with other cations. Preferred replacing cationsinclude tetraalkylammonium cations, metal ions, ammonium ions, hydrogenions, and mixtures of the above. Particularly preferred cations arethose which render the AMS-1Cr crystalline chromosilicate catalyticallyactive, especially for hydrocarbon conversion. These materials includehydrogen, ammonium ions, rare earth metals, aluminum, metals of GroupsIB, IIB and VIII of the Periodic Table of Elements, noble metals,manganese, etc., and other catalytically active materials and metalsknown to the art. Reference is made to the Periodic Table of Elements onpage 628 of WEBSTER'S SEVENTH NEW COLLEGIATE DICTIONARY, G. & C. MerriamCompany, Springfield, Mass., U.S.A. (1963). The catalytically activecomponents can be present anywhere from about 0.05 to about 25 weightpercent of the AMS-1Cr crystalline chromosilicate.

Members of the family of AMS-1Cr crystalline chromosilicates possessspecified and distinguishing crystalline structures.

X-ray diffraction patterns of various samples of AMS-1Cr crystallinechromosilicates were obtained by the following method: A Phillipsinstrument which utilized copper K alpha radiation was employed. Thetheta angles were recorded on a strip chart using a proportionalcounter. The theta values recorded were converted to interplanar spacingvalues in Angstroms (A) using the Bragg equation. The relativeintensities (relative peak heights) were calculated as (100 I/I_(o)),where I_(o) is the intensity of the strongest recorded peak and I is thevalue actually read for the particular interplanar spacing.

For ease of reporting the results, the relative intensities (relativepeak heights) were arbitrarily assigned the following values:

    ______________________________________                                        Relative Peak Height                                                                         Assigned Strength                                              ______________________________________                                        less than 10      VW     (very weak)                                          10-19             W      (weak)                                               20-39             M      (medium)                                             40-70             MS     (medium strong)                                      greater than 70   VS     (very strong)                                        ______________________________________                                    

The X-ray diffraction pattern showing the following significant lines inthe indicated relative intensities (relative peak heights) and assignedstrengths for the AMS-1Cr crystalline chromosilicate is shown in Table Ibelow:

                  TABLE I                                                         ______________________________________                                                         Relative                                                     Interplanar Spacings                                                                           Intensities                                                                             Assigned                                           d, A             I/I.sub.o Strength                                           ______________________________________                                        11.04 ± 0.2   100       VS                                                 10.04 ± 0.2   68        MS                                                 7.49 ± 0.2     2        VW                                                 6.70 ± 0.2     6        VW                                                 6.37 ± 0.1    10        W                                                  5.98 ± 0.1    20        M                                                  5.67 ± 0.1     9        VW                                                 5.53 ± 0.1    12        W                                                  5.34 ± 0.1     2        VW                                                 4.98 ± 0.1    10        W                                                  4.62 ± 0.08    5        VW                                                 4.35 ± 0.08    8        VW                                                 4.27 ± 0.08   12        W                                                  4.09 ± 0.08    2        VW                                                 4.02 ± 0.08    6        VW                                                 3.85 ± 0.07   85        VS                                                 3.72 ± 0.05   53        MS                                                 3.64 ± 0.05   36        M                                                  3.42 ± 0.05   10        W                                                  3.30 ± 0.05   10        W                                                  3.24 ± 0.05    4        VW                                                 3.12 ± 0.05    1        VW                                                 3.05 ± 0.03    8        VW                                                 2.98 ± 0.02   16        W                                                  2.96 ± 0.02   11        W                                                  2.85 ± 0.02    2        VW                                                 2.78 ± 0.02    2        VW                                                 2.74 ± 0.02    4        VW                                                 2.66 ± 0.02   23        M                                                  2.59 ± 0.02    3        VW                                                 2.55 ± 0.02    2        VW                                                 2.48 ± 0.02   26        M                                                  2.39 ± 0.02    4        VW                                                 2.26 ± 0.02    2        VW                                                 2.17 ± 0.02    9        VW                                                 2.00 ± 0.02   10        W                                                  1.99 ± 0.02   11        W                                                  ______________________________________                                    

The above X-ray pattern is characteristic of the AMS-1Cr crystallinechromosilicate having the oxide mole formula described in Expression I,which chromosilicate has been calcined at 1,100° F., wherein thetetraalkylammonium ion has been removed from the system by thecalcination procedure.

In the following Table, the stronger interplanar spacings are summarizedfor the AMS-1Cr chromosilicate from Table I above:

                  TABLE II                                                        ______________________________________                                        Interplanar Spacings                                                          d, A            Assigned Strength                                             ______________________________________                                        11.04 ± 0.2  VS                                                            10.04 ± 0.2  MS                                                            3.85 ± 0.07  VS                                                            3.72 ± 0.05  MS                                                            3.64 ± 0.05  M                                                             2.66 ± 0.02  M                                                             2.48 ± 0.02  M                                                             ______________________________________                                    

Such a calcination is now known to effect the removal of chromium oxidesfrom the framework of the AMS-1Cr crystalline chromosilicate molecularsieve, which oxides can be identified by X-ray diffraction. The X-raydiffraction pattern of Cr₂ O₃ includes an interplanar spacing of 2.67 Aat a relative intensity of 100; an interplanar spacing of 2.48 A at arelative intensity of 95; an interplanar spacing of 1.67 A at a relativeintensity of 90; an interplanar spacing of 3.63 A at a relativeintensity of 75; and an interplanar spacing of 2.17 A at a relativeintensity of 40. Chromium oxides were not detected by the X-raydiffraction technique until the chromium concentration with the sieveframework had been increased sufficiently to make the chromium oxidereflections obvious. It is to be noted that the ability to detectchromium oxide is only semi-quantitative, since pretreatment variablesin preparation and calcination exist and since the major Cr₂ O₃reflections are identical in interplanar spacing (d) with some of theX-ray reflections provided by the crystalline chromosilicate material.

In instances in which the AMS-1Cr crystalline chromosilicate is analyzedunder an X-ray diffraction pattern in an as-produced state (prior tohigh temperature treatment but after some reasonable amount of dryinghas taken place), the crystalline chromosilicate generally ischaracterized in Expression II above and has an X-ray diffractionpattern showing the following significant lines and assigned strengths:

                  TABLE III                                                       ______________________________________                                        Interplanar Spacings                                                          d, A            Assigned Strength                                             ______________________________________                                        11.04 ± 0.2  S                                                             10.04 ± 0.2  S                                                             9.71 ± 0.2   W                                                             8.84 ± 0.2   VW                                                            8.34 ± 0.2   VW                                                            7.89 ± 0.2   VW                                                            7.37 ± 0.2   W                                                             7.02 ± 0.2   VW                                                            6.70 ± 0.2   VW                                                            6.32 ± 0.1   W                                                             5.98 ± 0.1   W                                                             5.68 ± 0.1   W                                                             5.53 ± 0.1   W                                                             5.34 ± 0.1   VW                                                            5.09 ± 0.1   VW                                                            4.98 ± 0.1   W                                                             4.60 ± 0.08  W                                                             4.35 ± 0.08  W                                                             4.27 ± 0.08  W                                                             4.07 ± 0.08  VW                                                            4.00 ± 0.08  W                                                             3.80 ± 0.07  VS                                                            3.74 ± 0.05  M                                                             3.70 ± 0.05  S                                                             3.64 ± 0.05  MS                                                            3.46 ± 0.05  VW                                                            3.42 ± 0.05  W                                                             3.32 ± 0.05  W                                                             3.31 ± 0.05  W                                                             3.30 ± 0.05  W                                                             3.23 ± 0.05  VW                                                            3.14 ± 0.05  VW                                                            3.04 ± 0.03  W                                                             2.98 ± 0.02  W                                                             2.94 ± 0.02  W                                                             2.85 ± 0.02  VW                                                            2.78 ± 0.02  VW                                                            2.73 ± 0.02  W                                                             2.65 ± 0.02  VW                                                            2.60 ± 0.02  W                                                             2.56 ± 0.02  VW                                                            2.51 ± 0.02  VW                                                            2.48 ± 0.02  W                                                             2.44 ± 0.02  VW                                                            2.40 ± 0.02  VW                                                            2.39 ± 0.02  W                                                             2.10 ± 0.02  VW                                                            2.07 ± 0.02  VW                                                            2.00 ± 0.02  W                                                             1.996 ± 0.02 W                                                             1.96 ± 0.02  VW                                                            1.95 ± 0.02  W                                                             1.91 ± 0.02  W                                                             1.86 ± 0.02  W                                                             ______________________________________                                    

Please note that the assigned strengths presented in this Table III andin the following Table IV do not correspond to the intensities that aredefined hereinabove for assigned strengths. In these two tables, "S"approximates the defined "MS" in the list of assigned strengths.

In the following Table, the stronger interplanar spacings are summarizedfor AMS-1Cr crystalline chromosilicate from Table III above:

                  TABLE IV                                                        ______________________________________                                        Interplanar Spacings                                                          d, A            Assigned Strength                                             ______________________________________                                        11.04 ± 0.2  S                                                             10.04 ± 0.2  S                                                             3.80 ± 0.07  VS                                                            3.74 ± 0.05  M                                                             3.70 ± 0.05  S                                                             3.64 ± 0.05  MS                                                            ______________________________________                                    

The AMS-1Cr crystalline chromosilicates are useful in the hydrocrackingprocess. They appear to have relatively useful catalytic properties inpetroleum refining processes, such as the isomerization ofnormalparaffins and naphthenes, the reforming of certain feedstocks, theisomerization of aromatics, especially the isomerization ofpolyalkyl-substituted aromatics, such as xylenes, hydrodealkylation ofaromatics, the disproportionation of aromatics, the alkylation ofhydrocarbons, and the dewaxing of hydrocarbon streams. When used as acatalyst in isomerization processes with suitable cations placed on theion-exchangeable sites (M) within the AMS-1Cr crystallinechromosilicate, reasonably high selectivities for desired isomerizationtake place with feedstocks containing xylenes. In addition, impregnationof the chromosilicate with a metal, such as nickel, will furnishimproved isomerization of xylenes. The chromosilicates also possesssuperior transalkylation and disproportionation activities for aromaticscontaining ethyl groups.

In a broad embodiment, my invention relates to a crystallinechromosilicate having a composition in terms of oxides as follows:

    0.9±0.2[WR.sub.2 O+(1-W)M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein R is tetraalkylammonium, M is an alkali metal cation, W isgreater than 0 and less than or equal to 1, Y is at least 4, Z isbetween 0 and about 160 and having the X-ray diffraction patternsubstantially as described in Tables III or IV of the specificationhereinabove. For the sake of convenience, this embodiment will beidentified as the first crystalline chromosilicate. Preferably, Y is avalue between about 4 and about 200.

In a more preferred embodiment, W is a value between about 0.7 and about0.9, Y is a value between about 4 and about 200, and Z is a valuebetween about 0 and about 160.

In another broad embodiment, my invention relates to a crystallinechromosilicate having a composition in terms of mole ratios of oxides asfollows:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is between 4and about 500 and Z is between 0 and about 160, said chromosilicatehaving the X-ray diffraction lines and assigned strength substantiallyas described in Table I or Table II of the specification.Advantageously, Y is a value between about 4 and about 200.

In a more preferred embodiment, Y is a value within the range of about 4to about 100. Z can be a value between about 0 and about 40. In an evenmore preferred embodiment, Y is a value between about 4 and about 40.

Broadly, in accordance with the present invention there is provided acrystalline chromosilicate which comprises a molecular sieve materialproviding an X-ray diffraction pattern comprising the following X-raydiffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing  Assigned                                                 d, A                 Strength                                                 ______________________________________                                        11.04 ± 0.2       S                                                        10.04 ± 0.2       S                                                        3.80 ± 0.07       VS                                                       3.74 ± 0.05       M                                                        3.70 ± 0.05       S                                                        3.64 ± 0.05       MS                                                       ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2[WR.sub.2 O+(1-W)M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein R is an alkylammonium cation, M is at least one cation having avalence of n, Y is a value within the range of about 4 to about 500, Zis a value within the range of about 0 to about 160, and W is a valuethat is greater than or equal to 0 and less than or equal to 1. Thisrepresents the first crystalline chromosilicate, which is a precursor ofa second chromosilicate described hereinbelow. It is contemplated thatsuch chromosilicate precursor can also be prepared without an organictemplate, such as alkylammonium cation, wherein the value of W in theabove expression approaches and is equal to zero.

There is provided a second crystalline chromosilicate, which comprises amolecular sieve material providing an X-ray diffraction patterncomprising the following X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                         and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is within therange of about 4 to about 500, and Z is within the range of 0 to about160.

The first chromosilicate is a precursor of the second. Also, it iscontemplated that for either of the above two crystallinechromosilicates, advantageously, Y is a value within the range of about4 to about 200.

There is provided a catalytic composition, which composition comprises amixture of a crystalline chromosilicate and an oxide of chromium, saidcatalytic composition providing an X-ray diffraction pattern comprisingthe following X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

Consequently, according to the present invention, there is provided aprocess for the conversion of a hydrocarbon stream, which processcomprises contacting said stream under hydrocarbon conversion conditionswith a crystalline chromosilicate comprising a molecular sieve materialproviding an X-ray diffraction pattern comprising the following X-raydiffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

There is provided also a process for the conversion of a hydrocarbonstream, which process comprises contacting said stream under hydrocarbonconversion conditions with a catalytic composition comprising a mixtureof a crystalline chromosilicate and an oxide of chromium, said catalyticcomposition providing an X-ray diffraction pattern comprising thefollowing X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

Furthermore, according to the present invention, there is provided aprocess for the isomerization of a xylene feed, which process comprisescontacting said feed under isomerization conditions with a crystallinechromosilicate providing an X-ray diffraction pattern comprising thefollowing X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

There is provided a process for the isomerization of a xylene feed,which process comprises contacting said feed under isomerizationconditions with a catalytic composition comprising a mixture of acrystalline chromosilicate and an oxide of chromium, said compositionproviding an X-ray diffraction pattern comprising the following X-raydiffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2 M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

The AMS-1Cr crystalline chromosilicates can be used as catalysts or asadsorbents either in the alkali metal form (e.g., the sodium form), theammonium form, the hydrogen form, or any other univalent or multivalentcationic form. Mixtures of cations can be employed. The AMS-1Crcrystalline chromosilicates can also be used in intimate combinationwith a hydrogenating component such as tungsten, vanadium, molybdenum,rhenium, nickel, cobalt, chromium, manganese, or a noble metal such asplatinum or palladium, or rare earth metals, where ahydrogenation-dehydrogenation function is to be performed. Suchcomponents can be exchanged into the composition at the cationic sites,represented by the term "M" in the above formulae, impregnated therein,or physically and intimately admixed therewith. In one example, platinumcan be placed on the chromosilicate with a platinum-metal-containingion.

The original cation associated with the AMS-1Cr crystallinechromosilicate can be replaced, as mentioned above, by a wide variety ofother cations according to techniques which are known in the art. Ionexchange techniques known in the art are disclosed in many patentsincluding U.S. Pat. Nos. 3,140,249 3,140,251 and 3,140,253, theteachings of which are incorporated into this specification.

Following ion exchange, impregnation, or contact with another materialto place catalytically active materials within or on the chromosilicatestructure, the material can be washed and thereafter dried attemperatures in the range of about 150° F. (66° C.) to about 600° F.(316° C.). If the composition contains a mixture of chromosilicate andan oxide of chromium, it can be heated in an oxygen-containingatmosphere at closely regulated temperatures in a range from about 800°F. (427° C.) to about 1,700° F. (927° C.) for various periods of time.If the composition contains a chromosilicate that has been treatedpreviously in a hydrogen-containing atmosphere, the metal-containingchromosilicate should be treated in a hydrogen-containing atmosphereunder similar conditions.

For either treatment, a typical time for treatment falls within therange of about 0.2 hr to about 100 hr, preferably, within the range ofabout 1 hr to about 6 hr. Furthermore, a preferred temperature fallswithin the range of about 900° F. (482° C.) to about 1,200° F. (649°C.).

Ion exchange at the cationic site within the crystalline material willhave a relatively insignificant effect on the overall X-ray diffractionpattern that the crystalline chromosilicate material generates. Smallvariations may occur at various spacings on the X-ray pattern but theoverall pattern remains essentially the same. Small changes in the X-raydiffraction patterns may also be the result of processing differencesduring manufacture; however, the material will still fall within thegeneric class of AMS-1Cr crystalline chromosilicates defined in terms oftheir X-ray diffraction patterns specified herein.

The claimed crystalline chromosilicate may be incorporated as a purecrystalline material in a catalyst or may be admixed with variousbinders or bases depending upon the specific catalytic processing inwhich the crystalline chromosilicate is to be used. In many instances,the crystalline chromosilicate can be pelletized or extruded and used asa catalyst or an adsorbent. The crystalline chromosilicate can becombined with active or inactive materials, synthetic or naturallyoccurring zeolites, as well as inorganic or organic materials whichwould be useful for holding or binding the crystalline chromosilicate.Well-known materials include silica, silica-alumina, alumina sols,hydrated aluminas, clays such as bentonite or kaolin, or other binderswell known in the art. The crystalline chromosilicate content can varyanywhere from a few up to 100 percent of the total finished product.

It is contemplated that catalytically-active metals can be impregnatedonto the support, whether the catalytic support is solely a crystallinechromosilicate or a mixture of a chromosilicate and another material, inan amount that falls within the range of about 0.05 wt.% to about 25wt.%, based upon the weight of the total catalyst. Preferably, suchmetal or metals can be impregnated to an amount within the range ofabout 0.2 wt.% to about 16 wt.%, based upon the weight of the catalyst.

In the case of a cation-exchanged metal, the metal can be present in anamount that falls within the range of about 0.01 wt.% to about 10 wt.%,based upon the weight of the sieve material in the catalyst, preferably,within the range of about 0.1 wt.% to about 6 wt.%, based upon theweight of the sieve material.

The AMS-1Cr crystalline chromosilicate can be generally prepared bymixing in an aqueous medium, oxides of chromium in the +3 valence state,sodium or any other alkali metal and silicon, and a tetraalkylammoniumcompound or an alkylamine. The mole ratios of the various reactants canbe varied considerably to produce the AMS-1Cr crystallinechromosilicates. In particular, reactant mole ratios in terms of thevarious oxides for producing the AMS-1Cr crystalline chromosilicate canvary as is indicated in Table V below.

                  TABLE V                                                         ______________________________________                                        Ratios of Reactants                                                                             Mole Ratios                                                 ______________________________________                                        SiO.sub.2 /Cr.sub.2 O.sub.3                                                                     1-500                                                       R.sub.4 N.sup.+ /(R.sub.4 N.sup.+ + Na.sup.+)                                                   0.1-1                                                       OH.sup.- /SiO.sub.2                                                                             0.1-10                                                      ______________________________________                                    

wherein R is alkyl, and preferably propyl, and Na⁺ represents sodium,any other alkali metal, or an alkaline earth metal. The above quantitiescan be varied in concentration in the aqueous medium. It is generallypreferred that the mole ratio of water to the hydroxyl ion vary anywherefrom about 10 to about 500, or higher.

Under reasonably controlled conditions the claimed AMS-1Cr crystallinechromosilicate will be produced using the above mole ratios. Typicalreaction conditions include heating the reactants to a temperature ofanywhere from about 25° C. to about 300° C. for a period of time ofanywhere from about a few hours to a few weeks, or more. Preferredtemperature ranges are anywhere from about 150° C. to about 180° C. withan amount of time necessary for the precipitation and crystallization ofthe AMS-1Cr crystalline chromosilicate. Especially preferred conditionsinclude a temperature around 165° C. for a period of about 7 days.

The material thus formed can be separated by well-known means such asfiltration and recovered as a crystalline chromosilicate product. Thismaterial can be mildly dried for anywhere from a few hours to a few daysat varying temperatures to form a dry cake which itself can then becrushed to a powder, or to small particles, and extruded, pelletized, ormade into forms suitable for use as a catalyst or as an adsorbent.Typically, the material prepared after the mild drying conditions willcontain the tetraalkylammonium ion within the solid mass and asubsequent activation procedure is necessary, if it is desired to removethis material from the formed product.

Generally, the high-temperature treatment conditions will take place attemperatures anywhere from about 800° F. (427° C.) to about 1,600° F.(871° C.), or higher, e.g., 1,700° F. (927° C.). Extreme treatmenttemperatures may detrimentally alter the crystal structure, or destroyit. There is generally no need for going beyond about 1,200° F. (649°C.) in order to remove the tetraalkylammonium cation from the originalcrystalline material formed.

The high-temperature treatment is conducted in the presence of areducing atmosphere of hydrogen. As mentioned above, this treatmentshould be carried out for a period of time within the range of about 0.2hr to about 100 hr. A sample of the crystalline chromosilicate havingundergone such a high-temperature treatment in a reducing atmosphere ofhydrogen will provide an X-ray diffraction pattern, as described herein.

On the other hand, the chromosilicate material can be subjected to ahigh-temperature treatment in the presence of an oxygen-containingatmosphere, such as air. This treatment then becomes a calcinationtreatment. The resulting material is found to be a compositioncomprising a mixture of a crystalline chromosilicate and an oxide ofchromium. This composition provides an X-ray diffraction patterncomprising the following X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and has the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

Y is a value within the range of about 4 to about 500, and Z is a valuewithin the range of 0 to about 160.

This composition, a mixture of an oxide of chromium and a crystallinechromosilicate, has been found to be catalytically active for theconversion of hydrocarbons, e.g., the isomerization of a xylene feed.

It appears that the high-temperature treatment of the chromosilicatematerial in the presence of an oxygencontaining atmosphere operates toremove the chromium from the framework of the molecular sieve material.On the other hand, if the molecular sieve material is subjected to thehigh-temperature treatment in a reducing atmosphere of hydrogen, no freechromia is detectable in the chromosilicate. The hydrogen-treatedchromosilicate cation exchanges with mono and divalent cations in thetypical manner of conventional aluminosilicates. However, it has beenfound that if the hydrogen-treated chromosilicate is calcinedsubsequently in an oxygen-containing atmosphere and then analyzed byX-ray diffraction techniques, the resulting analysis shows that chromiais present in the sample that had been subjected to theoxygen-containing air at the high temperature. It appears that thisremoval of chromia from the chromosilicate structure is irreversible.

Consequently, there are three compositions which can result from theabove-described preparation techniques. Composition A is thechromosilicate material as prepared and only dried at a mildtemperature, e.g., 165° C. This composition has the defined X-raydiffraction pattern for the AMS-1Cr crystalline chromosilicate materialand does not have any detectable Cr₂ O₃. Composition A can be convertedto either Composition B, or Composition C, depending upon whichhigh-temperature treatment is given to the Composition A. Composition Cis made from Composition A, by heat treating the latter in a reducingatmosphere of hydrogen at a high temperature, as described hereinabove.This Composition C provides an X-ray diffraction pattern that is similarto the X-ray diffraction pattern provided by Composition A. On the otherhand, Composition B is made by heat treating Composition A orComposition C in an oxygen-containing atmosphere, such as air. It hasbeen found that if the chromium content of the reactant mixture issufficient, the X-ray diffraction analysis of the molecularsieve-containing product will show some detectable crystalline Cr₂ O₃ inthat sieve product. The Cr₂ O₃ and the crystalline chromosilicate arepresent as crystallites of an average diameter of about 500 A. Thedominant chromium oxide is CrO₃, when the Si-to-Cr mole ratios aregreater than 40. The relationships between Compositions A, B, and C areshown in the accompanying figure.

In view of the above, broadly, there is provided a method for preparinga crystalline chromosilicate, which method comprises: (1) preparing amixture containing an oxide of silicon, a compound of chromium, ahydroxide of an alkali metal or an alkaline earth metal, analkylammonium cation or a precursor of an alkylammonium cation, andwater; (2) maintaining said mixture at suitable reaction conditions toeffect formation of the chromosilicate, said reaction conditionscomprising a reaction temperature within the range of about 25° C. toabout 300° C., a pressure of at least the vapor pressure of water at thereaction temperature, and a reaction time that is sufficient to effectcrystallization to crystals of chromosilicate; and (3) washing anddrying said crystals.

Furthermore, there is provided the method which comprises furtheractivating said crystals of chromosilicate as prepared above by heattreating said crystals at a temperature within the range of about 800°F. (427° C.) to about 1,700° F. (927° C.) in the presence of ahydrogen-containing atmosphere.

There is provided, in addition, a method for preparing a catalyticcomposition, which method comprises: (1) preparing a mixture containingan oxide of silicon, a compound of chromium, a hydroxide of an alkalimetal or an alkaline earth metal, an alkylammonium cation or a precursorof an alkylammonium cation, and water; (2) maintaining said mixture atsuitable reaction conditions to effect formation of a crystallinematerial, said reaction conditions comprising a reaction temperaturewithin the range of about 25° C. to about 300° C., a pressure of atleast the vapor pressure of water at the reaction temperature, and areaction time that is sufficient to effect crystallization to crystalsof said chromosilicate; (3) washing and drying said crystals; and (4)calcining the resulting product in an oxygen-containing atmosphere at atemperature within the range of about 800° F. (427° C.) to about 1,700°F. (927° C.). Suitable compounds of chromium are Cr₂ (SO₄)₃.xH₂ O andCr(C₂ H₃ O₂)₃.H₂ O.

According to the present invention, there is provided a catalyticcomposition which comprises a crystalline chromosilicate and a porousrefractory inorganic oxide, said chromosilicate and said refractoryinorganic oxide having been intimately admixed with one another, saidchromosilicate comprising a molecular sieve material providing an X-raydiffraction pattern comprising the following X-ray diffraction lines andassigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

Furthermore, there is provided a catalytic composition which comprises amolecular-sieve-containing component and a porous refractory inorganicoxide, said component and said inorganic oxide having been intimatelyadmixed with one another, said component comprising a mixture of acrystalline chromosilicate and an oxide of chromium, providing an X-raydiffraction pattern comprising the following X-ray diffraction lines andassigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

There is provided a process for the conversion of a hydrocarbon stream,which process comprises contacting said stream under hydrocarbonconversion conditions with a catalytic composition comprising acrystalline chromosilicate and a porous refractory inorganic oxide, saidchromosilicate and said refractory inorganic oxide having beenintimately admixed with one another, said chromosilicate comprising amolecular sieve material providing an X-ray diffraction patterncomprising the following X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

There is provided a process for the isomerization of a xylene feed,which process comprises contacting said feed under isomerizationconditions with the catalytic composition comprising a crystallinechromosilicate and a porous refractory inorganic oxide, saidchromosilicate and said refractory inorganic oxide having beenintimately admixed with one another, said chromosilicate comprising amolecular sieve material providing an X-ray diffraction patterncomprising the following X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

There is provided a process for the conversion of a hydrocarbon stream,which process comprises contacting said stream under hydrocarbonconversion conditions with a catalytic composition comprising amolecular sieve-containing component and a porous refractory inorganicoxide, said molecular sieve-containing component and said inorganicoxide having been intimately admixed with one another, said molecularsieve-containing component comprising a mixture of a crystallinechromosilicate and an oxide of chromium, providing an X-ray diffractionpattern comprising the following X-ray diffraction lines and assignedstrengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

In addition, there is provided a process for the isomerization of axylene feed, which process comprises contacting said feed underisomerization conditions with a catalytic composition which comprises amolecular sieve-containing component and a porous refractory inorganicoxide, said molecular sieve-containing component and said inorganicoxide having been intimately admixed with one another, said molecularsieve-containing component comprising a mixture of a crystallinechromosilicate and an oxide of chromium, providing an X-ray diffractionpattern comprising the following X-ray diffraction lines and assignedstrengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160.

There are provided methods for preparing those catalytic compositionswhich have a molecular sieve-containing component and a porousrefractory inorganic oxide intimately admixed with one another. Themolecular sieve-containing component can be solely crystallinechromosilicate or it can be a mixture of a crystalline chromosilicateand an oxide of chromium.

There is provided a method for preparing the catalytic compositionhaving a crystalline chromosilicate and a refractory inorganic oxideintimately admixed with one another, which method comprises: (1)preparing a mixture of said chromosilicate in a finely-divided state anda sol, hydrosol, or a hydrogel of said refractory inorganic oxide; (2)thoroughly blending said mixture; (3) adding a gelling medium to thethoroughly-blended mixture to form a gel, if a sol or hydrosol ispresent; (4) drying said gel; and (5) heat treating said gel in ahydrogen-containing atmosphere at a temperature within the range ofabout 800° F. (427° C.) to about 1,700° F. (927° C.).

In addition, there is provided a method for preparing a catalyticcomposition which comprises a molecular sieve-containing component and aporous refractory inorganic oxide, said component and said inorganicoxide having been intimately admixed with one another, said componentcomprising a mixture of a crystalline chromosilicate and an oxide ofchromium, providing an X-ray diffraction pattern comprising thefollowing X-ray diffraction lines and assigned strengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.14 ± 0.2   M                                                            9.89 ± 0.2    VS                                                           3.85 ± 0.07   MS                                                           3.81 ± 0.07   M                                                            3.72 ± 0.05   M                                                            3.63 ± 0.05   M                                                            2.67 ± 0.02   M                                                            2.48 ± 0.02   M                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2 M.sub.2 /nO:Cr.sub.2 O.sub.3 : YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is a valuewithin the range of about 4 to about 500, and Z is a value within therange of 0 to about 160, which method comprises: (1) preparing a mixtureof said component in a finely-divided state and a sol, a hydrosol, or ahydrogel of a refractory inorganic oxide; (2) thoroughly blending saidmixture; (3) adding a gelling medium to the thoroughly-blended mixtureto form a gel, if a sol or hydrosol is present; (4) drying said gel; and(5) heat treating said gel in an oxygen-containing atmosphere at atemperature within the range of about 800° F. (427° C.) to about 1,700°F. (927° C.).

In the preparation of either of the above catalytic compositionscontaining a refractory inorganic oxide, it is contemplated that themolecular sieve-containing component can be cation exchanged prior toits introduction into the sol, hydrosol, or hydrogel of the refractoryinorganic oxide. Moreover, it is contemplated that either the molecularsieve-containing component prior to its introduction into the inorganicoxide sol or gel or the finished catalytic composition can beimpregnated with a catalytically active metal to form an impregnatedmaterial. The impregnated material is then dried and activated by a heattreatment in either an oxygen-containing atmosphere or ahydrogen-containing atmosphere, the selection of which is dependent uponwhether the chromosilicate in the composition has seen previously ahydrogen treatment or an oxygen treatment. Conditions for the drying andheat treating are provided hereinabove.

These catalytic compositions which contain a porous refractory inorganicoxide can be used suitably in processes for the conversion ofhydrocarbon streams. For example, there is provided a process for theconversion of a hydrocarbon stream, which process comprises contactingsaid stream under hydrocarbon conditions in the presence of either ofthese catalytic compositions. Furthermore, there is provided a processfor the isomerization of a xylene feed, which process comprisescontacting said feed under isomerization conditions in the presence ofeither of these two catalytic compositions which contain a refractoryinorganic oxide.

When the present AMS-1Cr crystalline chromosilicate is used as ahydrocracking catalyst, hydrocracking charge stocks can pass over thecatalyst at temperatures anywhere from about 500° F. (260° C.) to about850° F. (454° C.), or higher, using known molar ratios of hydrocarbon tohydrogen and varying pressures anyhere from a few up to many thousandsof pounds per square inch, or higher. The weight hourly space velocity(WHSV) and other process parameters can be varied consistent with thewell-known teachings of the art. For example, the pressure can bepresent within the range of about 20 psig (239 kPa) to about 2,500 psig(17,300 kPa); the WHSV, within the range of about 0.1 weight ofhydrocarbon per hour per weight of catalyst (hr⁻¹) to about 50 hr⁻¹, andthe mole ratio of hydrogen to hydrocarbon within the range of about 1 toabout 100.

The specified AMS-1Cr crystalline chromosilicate is also suitable as areforming catalyst to be used with the appropriate hydrogenationcomponents at well-known reforming conditions including temperatures ofanywhere from about 500° F. (260° C.) to 1,050° F. (566° C.), or higher,pressures anywhere from a few up to 300 psig (2,170 kPa) to 1,000 psig(6,998 kPa), and weight hourly space velocities andhydrocarbon-to-hydrogen mole ratios consistent with those well known inthe reforming art.

The present composition is also eminently suitable for hydrocarbonisomerization and disproportionation. Typically, isomerization can becarried out at a temperature within the range of about 200° F. (93° C.)to about 1,000° F. (538° C.), a hydrogen-to-hydrocarbon mole ratiowithin the range of about 0 to 35, a WHSV within the range of about 0.01hr⁻¹ to about 90hr⁻¹, and a pressure within the range of about 0 psig(102 kPa) to about 3,000 psig (20,800 kPa). Advantageously,isomerization can be conducted at a temperature within the range ofabout 300° F. (149° C.) to about 800° F. (427° C.), a pressure withinthe range of about 0 psig (102 kPa) to about 3,000 psig (20,800 kPa), aWHSV within the range of about 0.1 hr⁻¹ to about 50 hr⁻¹, and ahydrogen-to-hydrocarbon mole ratio within the range of 0 to about 35.

It is especially useful for liquid or vapor phase isomerization ofxylenes and especially for the isomerization of mixed xylenes topredominantly paraxylene products. Isomerization conditions for theisomerization of xylenes include temperatures of anywhere from about200° F. (93° C.) to about 1,000° F. (538° C.), hydrogen-to-hydrocarbonmole ratios of from about 0 to about 35, a weight hourly space velocity(WHSV) of about 0.01 weight unit of feed per hour per weight unit ofcatalyst (hr⁻¹) to about 90 hr⁻¹, and a pressure of about 0 psig (102kPa) to about 1,000 psig (6,998 kPa). Advantageously, the conditionscomprise a temperature of about 400° F. (204° C.) to about 900° F. (482°C.), a hydrogen-to-hydrocarbon mole ratio of about 0 to about 20, a WHSVof about 1 hr⁻¹ to about 20 hr⁻¹, and a pressure of about 50 psig (446kPa) to about 1,000 psig (6,998 kPa). The preferred conditions for theisomerization of xylenes comprise a temperature of about 600° F. (316°C.) to about 850° F. (454° C.), a hydrogen-to-hydrocarbon mole ratio ofabout 2 to about 8, a WHSV of about 1 hr⁻¹ to about 10 hr⁻¹, and apressure of about 100 psig (793 kPa) to about 300 psig (2,170 kPa).

A suitable xylene feed for the isomerization process of the presentinvention is one that contains less than the thermodynamic-equilibriumconcentration of the desired xylene isomers. For example, if one wantsto obtain p-xylene, he will employ a feed that contains p-xylene in aconcentration that is less than the amount provided by thermodynamicequilibrium.

The choice of catalytically active metals to be placed on the AMS-1Crcrystalline chromosilicate can be selected from any of those well knownin the art. Nickel, molybdenum, or a mixture thereof seem to beespecially appropriate for isomerization of aromatics. When used as acatalyst in isomerization processes with suitable cations placed on theion-exchangeable sites within the AMS-1Cr crystalline chromosilicate,reasonably high selectivities for production of desired isomers areobtained.

The claimed AMS-1Cr crystalline chromosilicates can be used asadsorbents to selectively adsorb specific isomers or hydrocarbons ingeneral from a liquid or vapor stream.

The following examples are presented for the purpose of illustrationonly and are not intended to limit the scope of the present invention.They should not be read to unduly limit or restrict the scope of theappended claims.

EXAMPLE I

The AMS-1Cr crystalline chromosilicate was prepared by dissolving 0.7 gmof Cr₂ (SO₄)₃.xH₂ O in 60 gm of distilled water. To this solution wasadded 2.6 gm of NaOH. The Cr(III) precipitated as the flocculenthydroxide. To the resultant slurry, 10.2 gm of tetra-n-propylammoniumbromide (TPABr) were added and the mixture was stirred until the TPABrwas dissolved. To this slurry, 13.5 gm of Ludox-AS (30% solids) wereadded in 4 increments with vigorous stirring. The resulting greenishcolloidal solution was placed in a reaction vessel and sealed. Thevessel was placed in an oven at 165° C. and left there for 7 days. Atthe end of this time, the vessel was opened and the contents wereremoved. The crystalline material was filtered from the mother liquorand was washed with copious quantities of water. The crystallinematerial was dried in a forced air drying oven at 165° C. and thencharacterized by X-ray diffraction (XRD). XRD observed 100%crystallinity with the AMS-1Cr pattern for this material reported inTable I above. The yield was approximately 2 gm.

EXAMPLE II

A second preparation of the AMS-1Cr crystalline chromosilicate molecularsieve was performed at slight scale-up and with an alteration of thesteps in Example I. A 2.33-gm portion of Cr₂ (SO₄)₃.xH₂ O was dissolvedin 20 gm of H2O at 190° F. (88° C.). A 8.7 gm quantity of NaOH was addedwhich resulted in a vigorous evolution of heat. The Cr(III) wasapparently in solution as NaCrO₂. When 180 gm of H₂ O were added to thissolution, some Cr(III) did precipitate as the hydroxide. To this slurrywere added 31.8 gm of TPABr, which dissolved in the slurry. Finally, 45gm of Ludox were added in approximately 4 increments in as short a timeperiod as possible. The resulting greenish milky slurry was placed inreaction vessels and then sealed. The vessels were placed in an oven for7 days at 165° C. After this time period, the vessels were opened andthe contents were filtered. The resulting crystalline material waswashed with copious quantities of water and then dried in a forced airoven. Again XRD showed 100% crystallinity for the material with thetypical AMS-1Cr pattern. The yield of solids was 6.2 gm.

EXAMPLE III

In this example, the AMS-1Cr crystalline chromosilicate of Example I wasused.

The crystalline material was calcined at 1,100° F. for 4 hours in air toremove the organic base. The calcined AMS-1Cr material was exchangedwith a solution of 20 gm of NH₄ NO₃ in 200 milliliters of H₂ O and asecond time with 20 gm of NH₄ (C₂ H₃ O₂) in 200 ml of H₂ O, both at 190°F. (88° C.) for 2 hours. The exchanged chromosilicate was dried andcalcined in air by heating to 900° F. (482° C.) in 4 hours, maintainingthe chromosilicate at 900° F. (482° C.) for 4 hours and then cooling to100° F. (37.8° C.) in 4 hours. The calcined material was exchanged with100 ml of a 5% Ni(NO₃)₂.6H₂ O solution for 2 hours at 190° F. (88° C.).The sieve was dried and calcined again using the above calcinationprocedure.

About 1 gm of the above chromosilicate was dispersed with 6 grams ofPHF-Al₂ O₃ hydrosol (8.7% solids), obtained from the American CyanamidCompany, and mixed thoroughly. One milliliter of distilled water and 1ml of conc. NH₄ OH were mixed and then added to the slurry withintensive mixing. The AMS-1Cr-Al₂ O₃ gel was placed in the drying ovenat 165° C. for 4 hours. The dried solid was again calcined via the aboveprocedure. The calcined catalyst was crushed to 30-50 mesh and activatedvia a fourth programmed calcination.

The calcined catalyst contained 65 weight percent chromosilicate and 35weight percent amorphous alumina with approximately 0.5 weight percentof the total catalyst as nickel. This material was analyzed by X-raydiffraction and is reported in Table 1 above.

One gram of the sized and activated catalyst was placed in amicroreactor and sulfided with H₂ S for 20 minutes at room temperature.The catalyst was then placed under H₂ pressure and heated to 600° F.(316° C.). After 1 hour, feed was passed through the microreactor underthe following once-through operating conditions:

    ______________________________________                                        Temperature        800° F. (427° C.)                            Pressure           150 psig (1,136 KPa)                                       WHSV               5.53 hr.sup.-1                                             H/HC mole ratio    7                                                          ______________________________________                                    

The liquid feed and liquid effluent streams for this operation are shownbelow. Because of the equipment limitations on the testing unit, onlythe liquid streams were specifically reported. The amount of light endsproduction over this catalyst was determined to be low from the gaschromatographic analysis made on the off-gas stream from the testingunit. The volume of off-gas was, from past performance, determined tonot substantially reduce liquid yields of the catalyst.

    ______________________________________                                                          Liquid     Liquid                                                             Feed,      Product,                                         Component         wt %       wt %                                             ______________________________________                                        Paraffins and naphthenes                                                                        .03        .02                                              Benzene           --         3.80                                             Toluene           .077       .39                                              Ethylbenzene      19.71      13.28                                            Paraxylene        --         17.54                                            Metaxylene        79.80      52.27                                            Orthoxylene       .38        10.71                                            C.sub.9, totals              .29                                              Methylethylbenzene           .13                                              Trimethylbenzene             .15                                              Normal propylbenzene         .01                                              C.sub.10, totals             1.70                                             Diethylbenzenes              1.32                                             1,3 Diethylbenzenes          .67                                              1,4 & 1,2 Diethylbenzenes    .65                                              Dimethylethylbenzenes        .38                                              ______________________________________                                    

EXAMPLE IV

In this Example, crystalline chromosilicate prepared in a manner similarto that described in Example I was exposed to high temperaturecalcination as described in Example II and analyzed to determine itsoxide composition. The results are reported below.

    ______________________________________                                        Product Composition, wt %                                                     SiO.sub.2              80.00                                                  Cr.sub.2 O.sub.3       12.40                                                  Na.sub.2 O             5.39                                                   Al.sub.2 O.sub.3       0.18                                                   Fe.sub.2 O.sub.3       0.11                                                   Volatiles*             1.92                                                                          100.00                                                 Mole Ratios                                                                   SiO.sub.2 /Cr.sub.2 O.sub.3                                                                          16.3                                                   Na.sub.2 O/Cr.sub.2 O.sub.3                                                                          1.1                                                    SiO.sub.2 /Al.sub.2 O.sub.3                                                                          757.6                                                  SiO.sub.2 /Fe.sub.2 O.sub.3                                                                          1,960.8                                                SiO.sub.2 /(Al.sub.2 O.sub.3 + Fe.sub.2 O.sub.3)                                                     546.4                                                  ______________________________________                                         *Assumed valvue to give 100%.                                            

EXAMPLE V

Another example of AMS-1Cr chromosilicate was prepared. A 4.8-gm portionof Cr₂ (SO₄)₃.xH₂ O was dissolved in 200.0 gm of distilled H₂ O at 90°C. Then 5.2 gm of NaOH were added to the stirred solution and dissolvedtherein. Initially, a gelatinous solid of chromium hydroxide formed, butas more NaOH dissolved, the amphoteric chromium hydroxide redissolved,presumably as sodium chromite. To the basic solution were added 31.2 gmof tetraethylammonium bromide (TEABr). The TEABr was dissolved in thesolution. Finally, 40.6 gm of Ludox AS-30 was added with vigorousstirring. The resulting slurry was divided and transferred to threetubular crystallizers. The slurry was crystallized at 165° C. for 7days. The solid material was washed with approximately 1 liter ofdistilled H₂ O and then dried at 165° C. for 20 hrs. A sample of thedried material was submitted for XRD analysis and was found to be acrystalline AMS-B 1Cr. The yield was 13.8 gm. The remaining solid wascalcined at 1,000° F. (538° C.) in air for 4 hrs and was also analyzedby XRD. It was found to be a mixture of crystalline AMS-1Crchromosilicate and Cr₂ O₃. No attempt was made to quantify the Cr₂ O₃.

EXAMPLE VI

Another embodiment of a crystalline AMS-1Cr was prepared. First, 3.6 gmof Cr₂ (SO₄)₃.xH₂ O were dissolved in 200 ml of distilled H₂ O at 90° C.To the greenish-blue solution was added 5.4 gm of NaOH. After theinitial precipitate dissolved, 31.2 gm of TEABr was added and dissolved.To this final solution, 38.2 gm of Ludox AS-30 was added quickly, andthe resultant solution was stirred for approximately 10 minutes. Theresulting slurry was divided between three tubular crystallizers andcrystallized at 165° C. for 7 days. After crystallization, the solidmaterial was filtered from the crystallization solution and washed withapproximately 1 liter of distilled water. The solid material was driedin a forced air oven at 165° C. overnight (approximately 16 hr). XRDanalysis of the dried material showed no amorphous band but the peakshad a relatively low set of intensities suggesting the possibility ofSiO₂. The remainder of the material was calcined in air at 1,000° F.(538° C.) for 4 hours. XRD analysis showed only 50% crystalline AMS-1Crwith Cr₂ O₃ present.

EXAMPLE VII

For another embodiment of crystalline AMS-1Cr, the following quantitiesof reactants were used to obtain the initial slurry, as described inExample IV: 2.4 gm of Cr₂ (SO₄)₃.xH₂ O; 200.0 gm of distilled H₂ O; 2.0gm of NaOH; 31.5 gm of TPABr; and 38.2 gm of Ludox AS-30. The slurry wascrystallized for 7 days at 165° C. The solid material was removed fromthe crystallizer, washed with approximately 1 liter of distilled H₂ O,and dried at 165° C. The dried material was then calcined in air at1,000° F. for 4 hours with a linear heating rate requiring 4 hours to gofrom 200° F. (93° C.) to 1,000° F. (538° C.). The calcined material wasa yellow green instead of the typical Cr₂ O₃ green for higher chromiumconcentration factors. XRD analysis indicated a 100% crystalline AMS-1Crplus Cr₂ O₃.

EXAMPLE VIII

Additional samples of AMS-1Cr were prepared in a manner similar to thatdescribed in the preceding examples. The quantities of reactants used ineach of these preparations are presented hereinbelow in Table VII. Theamount of chromium that was employed in each preparation is expressed interms of a "chromium factor". In each case, the crystallizationtemperature was maintained at 165° C. and the crystallization wascarried out for a period of 7 days. After drying, each sample wascalcined in air for 4 hr at a temperature of 1,000° F. (538° C.).

These results show that as the chromium factor became larger, more andmore Cr₂ O₃ was detected in the product.

EXAMPLE IX

Samples Nos. 7, 8, 9, and 10, that were prepared in Example VIII, wereused in Catalysts Nos. 2, 3, 4, and 5, respectively.

A 5-gm portion of the Sample No. 7 was ion exchanged with an ammoniumacetate solution that had been prepared by dissolving 50 gm of the saltin 500 ml of distilled water at 90° C. for 2 hours. The solid materialwas filtered from the exchange solution and washed with 200 ml ofdistilled water. The exchange was repeated and the filtered solid waswashed with 300 ml of distilled water. The solid material was dried at165° C. for 2 days and then calcined in air at 900° F. (482° C.) for 4hr. The calcined material was exchanged with a solution that had beenprepared by dissolving 12.8 gm of Ni(NO₃)₂.6H₂ O in 250 ml of distilledwater at 90° C. for 3 hr. The solid was filtered from the exchangesolution and washed with 250 ml of distilled water. The exchanged solidwas dried at 165° C. for 3 hr and then calcined at 900° F. (482° C.)overnight. The calcined solid weighed 3.9 gm and was dispersedthoroughly in 25.3 gm of a PHF-Al₂ O₃ hydrosol (10.7 wt.% Al₂ O₃)obtained from the American Cyanamid Company. To the dispersed slurry wasadded a solution of 2 ml of concentrated NH₄ OH and 2 ml of distilled H₂O to gel the suspended solid in the alumina. The gel was dried at 165°C. in a forced air oven for 4 hr. The dried solid was then calcined at900° F. (482° C.) overnight.

                                      TABLE VII                                   __________________________________________________________________________    ADDITIONAL CATALYST PREPARATIONS                                              Sample No.  7     8     9     10    11    12      13                          __________________________________________________________________________    Dist. H.sub.2 O, gm                                                                       180.0 1,600.0                                                                             1,000.0                                                                             1,000.0                                                                             200.0 200.0   200.0                       Cr.sub.2 (SO.sub.4).sub.3 × xH.sub.2 O, gm                                          2.33  28.8  24.0  24.0  7.2   9.6     14.4                        Chromium Factor                                                                           X1    X1.5  X2    X3    X3    X4      X6                          NaOH, gm    8.7   41.6  26.0  20.8  9.2   11.2    15.2                        TPABr, gm   31.8  249.6 156.0 156.0 31.2  31.2    31.2                        Ludox HS-40, gm                                                                           45.0.sup.1                                                                          305.6 191.0 142.2 29.0  29.0    29.0                        XRD.sup.2 Results                                                                         50%   AMS-1Cr                                                                             AMS-1Cr                                                                             AMS-1Cr                                                                             AMS-1Cr                                                                             SOME    PRIMARILY                               CRYST.                                                                              +     +     +     +     AMS-1Cr,                                                                              Cr.sub.2 O.sub.3                        AMS-1Cr                                                                             Cr.sub.2 O.sub.3                                                                    Cr.sub.2 O.sub.3                                                                    Cr.sub.2 O.sub.3                                                                    Cr.sub.2 O.sub.3                                                                    MOSTLY                                                                        Cr.sub.2 O.sub.3                    __________________________________________________________________________     .sup.1 Ludox HS30 was used.                                                   .sup.2 XRD = Xray Diffraction.                                           

This catalyst, identified hereinafter as Catalyst No. 2, was prepared tocontain 65 wt.% of the nickel-exchanged solid and 35 wt.% ofgamma-alumina. Catalyst No. 2 was crushed and sized to a 30-to-50-meshmaterial, i.e., a material that would pass through a 30-mesh screen(U.S. Sieve Series), but be retained on a 50-mesh screen (U.S. SieveSeries). The sized material was then calcined in air for 4 hr at atemperature of 900° F. (482° C.).

A 1-gm portion of the calcined Catalyst No. 2 was placed in amicroreactor and sulfided by passing H₂ S over the catalyst at the rateof 0.2 ft³ /hr for 20 minutes. The microreactor was pressurized withflowing hydrogen to 150 psig (1,138 kPa) and at a flow of 0.3 ft³ /hr.The temperature was increased from room temperature to 800° F. (427° C.)in 3 hr. A synthetic reject filtrate of mixed xylenes was passed overthe catalyst at a WHSV of approximately 6 hr⁻¹, a pressure of 150 psig(1,138 kPa), and a hydrogen rate of 0.3 cu ft per hr. The liquid productwas collected and analyzed by gas-chromatographic techniques. Theresults for the evaluation of this catalyst are shown in Table VIII.This sieve in the catalyst was only 50% crystalline after the initialcalcination and the low xylene isomerization activity for this catalystis believed to reflect the degree of crystallinity.

A 30-gm portion of Sample No. 8 was ion-exchanged at a temperature of90° C. for 1 hr with stirring with a solution that had been prepared bydissolving 30 gm of ammonium acetate in 300 ml of distilled water.Similarly, a 60-gm portion of Sample No. 9 was ion-exchanged at atemperature of 90° C. for 1.5 hr with a solution that had been preparedby dissolving 60 gm of ammonium acetate in 300 ml of distilled water.Each exchanged solid was filtered from its exchange solution and washedwith 200 ml of distilled water. This exchange for each solid wasrepeated 4 times. The final exchange was followed with a300-ml-distilled-water wash. Each solid was then dried at 165° C. for 3hr and then transferred to the calcining furnace for a programcalcination at 900° F. (482° C.) overnight. The program calcinationrequired 3.5 hours to heat from 200° F. (93° C.) to 900° F. (482° C.), 4hours at 900° F. (482° C.) and a minimum of 3.5 hours to cool to 200° F.(93° C.). Each calcined solid was exchanged with a quantity of 5 wt%solution of Ni(NO₃)₂.6H₂ O for 1.5 hr at 90° C., wherein Sample No. 8used 150 ml of solution and Sample No. 9 used 200 ml of exchangesolution. Each exchanged solid was washed with 150 ml of distilled waterand filter-dried overnight. The solids were dried at 165° C. for 6 hoursand then transferred to the calcining furnace to program calcine in airat 900° F. (482° C.) overnight.

                                      TABLE VIII                                  __________________________________________________________________________    TEST NO. 2; CATALYST NO. 2                                                                Cut No.                                                                       FD.sup.1                                                                           1    2    3    4    5                                        __________________________________________________________________________    Temperature, °F.                                                                        800  800  920  920  920                                        °C.     427  427  493  493  493                                      Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                    --   --   --   .10  .16  .09                                      Benzene     --   .55  .11  .35  .26  .30                                      Toluene     .03  --   --   .13  .13  .14                                      Ethylbenzene (EB)                                                                         20.97                                                                              18.94                                                                              19.91                                                                              22.4 21.74                                                                              22.4                                     p-Xylene (pX)                                                                             --   6.30 2.96 7.37 5.43 5.88                                     m-Xylene (mX)                                                                             78.5 70.6 75.0 65.5 69.0 68.00                                    o-Xylene (oX)                                                                             --   3.62 2.06 4.03 3.02 3.22                                     C.sub.9.sup.+                                                                             .5   --   --   .12  .25  --                                       Calculated Results                                                            pp H.sub.2, psia 147.1                                                                              152.2                                                                              154.0                                                                              148.5                                                                              152.0                                    H/HC             8.4  12.1 14.5 9.1  11.9                                     t.sub.c, sec.    2.77 2.87 2.65 2.55 3.54                                     WHSV, hr.sup.-1  5.19 3.58 3.01 4.76 3.64                                     pX PATE, %       33.4 15.8 40.4 29.2 32.0                                     mX PATE, %       25.0 12.2 29.3 31.0 22.8                                     oX PATE, %       16.8 8.71 18.9 13.5 14.5                                     EB Conv., %      9.7  5.1                                                     Time On Oil, hr  16.0 40   112  184  217                                      __________________________________________________________________________     .sup.1 FD = Feed                                                         

Each of the solids was dispersed in PHF-Al₂ O₃ hydrosol, obtained fromthe American Cyanamid Company, to make a catalyst composed of 65%nickel-exchanged solid in 35% gamma Al₂ O₃. The 30 gm of exchangedSample No. 8 used 185.9 gm of hydrosol and the 60 gm of exchanged SampleNo. 9 used 371.4 gm of hydrosol (10.7% solids). Each exchanged materialwas thoroughly dispersed in hydrosol by mixing for approximately 45minutes. A solution, consisting of 50 vol% of distilled H₂ O and 50 vol%of concentrated NH₄ OH, was added to gel the slurry. The mixturecontaining Sample No. 8 used 22 ml of this solution, while the mixturecontaining Sample No. 9 used 37 ml. Each gelled mass was dried at 165°C. for 3 hr in a forced air drying oven with frequent turning tofacilitate drying. The dried material was then program calcined at 900°F. (482° C.) for 4 hr with an additional 4 hr of drying at 200° F. (93°C.) added to the beginning of the program. The calcined material wascrushed and sized to obtain a 30-to-50-mesh material, i.e., a materialthat will pass through a 30-mesh screen (U.S. Sieve Series), but beretained on a 50-mesh screen (U.S. Sieve Series). The catalystcontaining Sample No. 8 material is identified hereinafter as CatalystNo. 3, while the catalyst containing Sample No. 9 material is identifiedhereinafter as Catalyst No. 4.

A 1-gm portion of Catalyst No. 3 was tested for its ability to catalyzethe isomerization of a xylene feed, as was done with Catalyst No. 2. Theresults of this test, Test No. 3, are presented hereinafter in Table IX.In a like manner, a 1-gm portion of Catalyst No. 4 was tested in a test,identified hereinafter as Test No. 4. The results of Test No. 4 arepresented hereinafter in Table X. The tests were conducted at a pressureof 150 psig (1,138 kPa) and a hydrogen flow rate of 0.3 cu ft per hr.The time on oil is expressed as the total time to the end of theparticular cut.

A portion of Sample No. 10 was prepared into a catalyst and tested forxylene isomerization in a manner similar to that used hereinabove forCatalyst No. 2 and Catalyst No. 3. This catalyst is identifiedhereinafter as Catalyst No. 5 and its test, as Test No. 5. The resultsof Test No. 5 are shown in Table XI.

The relative comparisons of PATEs for the three xylene isomers indicatethat this catalyst prepared from a Composition B material exhibits shapeselectivity for xylene isomerization. The basic indication for shapeselectivity is the high PATE values for ortho-xylene and para-xylenewhen compared to meta-xylene. This particular evaluation has beenindicated by tests run on the AMS-1 family sieves using an 80%m-xylene/20% ethylbenzene feed. The material designated Composition Bdoes not consistently show the shape selective characteristic. Thiscatalyst is the only material other than the material of Examples I andIII to demonstrate shape selectivity.

EXAMPLE X

This example describes the procedure used to detect the presence of Cr₂O₃ in the air-calcined material herein described as Composition B. TheX-ray diffraction procedure for determining free Cr₂ O₃ in a AMS-typemolecular sieve is based on the ratio of the integrated intensities ofthe sum of the 2.67 A and 2.65 A peaks, divided by the intensity of the2.73 A peak. Physical blends of sieve and Cr₂ O₃ over the concentrationrange desired serve as calibration standards. The peak at 2.56 A is thestrongest XRD peak characteristic of Cr₂ O₃. It is frequently notwell-resolved from the 2.65 A sieve peak; hence, the use of a sum. The2.73 A peak is a convenient, well-resolved sieve peak which acts as aninternal standard to make the measurements independent of manyexperimental variables. Copper K radiation monochromatized by a graphitecrystal was used for all experiments. Samples were slow scanned at0.125° two-theta per minute and peak areas were measured by planimetry.

                                      TABLE IX                                    __________________________________________________________________________    TEST RESULTS - TEST NO. 3                                                     CATALYST NO. 3                                                                            Cut No.                                                                       FD.sup.1                                                                         1   2   3   4   5   6   7   8   9   10  11  12                 __________________________________________________________________________    Temperature, °F.                                                                      800 800 840 800 840 800 800 800 840 840 880 880                  °C.   427 427 449 427 449 427 427 427 449 449 471 471                Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                    .05                                                                              .01 .02 .02 .02 .02 .02 .03 .05 .05 .01 .03 .08                Benzene     -- .67 .60 .90 .66 1.00                                                                              .57 .33 .42 .51 .62 1.00                                                                              1.95               Toluene     .07                                                                              .15 .14 .18 .15 .20 .13 .11 .12 .12 .14 .21 .29                Ethylbenzene (EB)                                                                         19.56                                                                            17.96                                                                             17.98                                                                             17.54                                                                             18.01                                                                             17.42                                                                             18.12                                                                             18.50                                                                             18.29                                                                             18.15                                                                             17.97                                                                             17.24                                                                             16.48              p-Xylene (pX)                                                                             8.65                                                                             17.21                                                                             16.92                                                                             17.96                                                                             17.17                                                                             18.23                                                                             16.72                                                                             14.50                                                                             15.98                                                                             16.05                                                                             16.90                                                                             18.12                                                                             18.47              m-Xylene (mX)                                                                             47.83                                                                            42.06                                                                             42.17                                                                             41.55                                                                             41.98                                                                             41.36                                                                             42.11                                                                             43.50                                                                             42.53                                                                             42.58                                                                             41.98                                                                             41.34                                                                             42.91              o-Xylene (oX)                                                                             23.66                                                                            21.37                                                                             21.53                                                                             21.05                                                                             21.44                                                                             20.89                                                                             21.75                                                                             22.70                                                                             22.00                                                                             22.12                                                                             21.85                                                                             21.20                                                                             19.84              C.sub.9.sup.+                                                                             .22                                                                              .57 .64 .82 .57 .88 .58 .33 .61 .44 .53 .86 --                 Diethylbenzene                                                                            -- .31 .35 .40 .28 .42 .31 .13 .26 .20 .25 .38 --                 Calculated Results                                                            ppH.sub.2, psia                                                                              140.6                                                                             140.2                                                                             141.0                                                                             141.4                                                                             145.9                                                                             145.3                                                                             102.1                                                                             147.4                                                                             139.3                                                                             138.5                                                                             139.6                                                                             --                 H/HC           5.8 5.7 6.0 6.1 7.8 7.5 3.1 8.5 5.5 5.3 5.6 --                 t.sub.c, sec.  2.65                                                                              2.64                                                                              2.57                                                                              2.66                                                                              2.66                                                                              2.74                                                                              1.92                                                                              2.78                                                                              2.54                                                                              2.53                                                                              2.47                                                                              --                 WHSV, hr.sup.-1                                                                              6.57                                                                              6.68                                                                              6.43                                                                              6.31                                                                              4.93                                                                              5.12                                                                              12.23                                                                             4.49                                                                              6.97                                                                              7.24                                                                              6.88                                                                              --                 pX PATE, %     83.4                                                                              80.6                                                                              91.5                                                                              83.1                                                                              94.3                                                                              78.7                                                                              56.7                                                                              71.6                                                                              72.2                                                                              80.6                                                                              93.4                                                                              95.6               mX PATE, %     99.6                                                                              97.7                                                                              104.5                                                                             100.5                                                                             106.8                                                                             98.3                                                                              76.5                                                                              90.8                                                                              89.6                                                                              99.0                                                                              105.9                                                                             86.1               oX PATE, %     59.2                                                                              55.2                                                                              70.5                                                                              57.2                                                                              74.1                                                                              49.6                                                                              27.3                                                                              43.1                                                                              44.2                                                                              51.0                                                                              71.4                                                                              112.3              EB Conv., %    8.2 8.1 10.3                                                                              7.9 10.9                                                                              7.4 5.4 6.5 7.2 8.1 11.9                                                                              15.7               Time On Oil, hr                                                                              16.5                                                                              24.0                                                                              41.25                                                                             48.0                                                                              64.5                                                                              72.25                                                                             88.0                                                                              95.6                                                                              112.0                                                                             119.0                                                                             136.0                                                                             143.0              __________________________________________________________________________     .sup.1 FD =  Feed                                                        

                                      TABLE X                                     __________________________________________________________________________    TEST RESULTS - TEST NO. 4                                                     CATALYST NO. 4                                                                            Cut No.                                                                       FD.sup.1                                                                           1    2    3    4    5    9    10   11                        __________________________________________________________________________    Temperature, °F.                                                                        800  800  840  800  840  840  840  880                         °C.     427  427  449  427  449  449  449  471                       Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                    .05  .04  .03  .02  .03  .03  .06  .04  .02                       Benzene     --   .88  .80  1.20 .92  1.65 1.13 1.16 1.13                      Toluene     .07  .16  .15  .20  .17  .25  .17  .19  .22                       Ethylbenzene (EB)                                                                         19.56                                                                              17.53                                                                              17.71                                                                              17.02                                                                              17.47                                                                              16.37                                                                              17.19                                                                              17.12                                                                              17.21                     p-Xylene (pX)                                                                             8.65 17.30                                                                              16.91                                                                              17.93                                                                              17.16                                                                              18.49                                                                              17.65                                                                              17.85                                                                              18.17                     m-Xylene (mX)                                                                             47.83                                                                              42.18                                                                              42.35                                                                              41.78                                                                              42.07                                                                              41.42                                                                              41.84                                                                              41.69                                                                              41.27                     o-Xylene (oX)                                                                             23.66                                                                              21.19                                                                              21.45                                                                              20.97                                                                              21.30                                                                              20.62                                                                              21.22                                                                              21.14                                                                              21.15                     C.sub.9.sup.+                                                                             .22  .62  .62  .88  .88  1.17 .74  .81  .83                       Diethylbenzene                                                                            --   .43  .37  .48  .51  .61  .38  .42  .36                       Calculated Results                                                            ppH.sub.2, psia  144.0                                                                              131.6                                                                              134.5                                                                              135.1                                                                              142.0                                                                              140.0                                                                              134.6                                                                              138.0                     H/HC             6.9  4.8  4.4  4.6  6.2  5.7  4.5  5.2                       t.sub.c , sec.   2.71 2.48 2.46 2.55 2.59 2.56 2.46 2.44                      WHSV, hr.sup.-1  5.51 9.61 8.61 8.39 6.13 6.76 8.57 7.40                      pX PATE, %       84.2 80.4 90.9 83.1 96.8 88.1 90.1 94.0                      mX PATE, %       97.9 95.3 101.8                                                                              98.5 106.3                                                                              101.1                                                                              103.2                                                                              106.5                     oX PATE, %       63.8 58.11                                                                              73.4 60.2 81.4 67.1 69.0 72.3                      EB Conv., %      10.4 9.5  13.0 10.7 16.3 12.1 12.5 12.0                      Time On Oil, hr  16.6 24.1 41.35                                                                              48.1 113.1                                                                              160.6                                                                              167.6                                                                              184.6                     __________________________________________________________________________     .sup.1 FD = Feed                                                         

                                      TABLE XI                                    __________________________________________________________________________    TEST RESULTS - TEST NO. 5                                                     CATALYST NO. 5                                                                            Cut No.                                                                       FD.sup.1                                                                            1    2    3    4    5    6    7    8    9                   __________________________________________________________________________    Temperature, °F.                                                                         800  800  840  840  840  880  878  882  880                   °C.      427  427  449  449  449  471  470  472  471                 Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                    .05        .05  .07  .02  .05  --   .05  --   --                  Benzene     --    .76  .67  1.07 1.10 1.67 1.93 1.97 2.00 2.04                Toluene     .07   .13  .11  .23  .16  .24  .27  .27  .28  .26                 Ethylbenzene (EB)                                                                         19.56 18.29                                                                              18.39                                                                              17.40                                                                              17.39                                                                              16.53                                                                              16.68                                                                              16.52                                                                              16.36                                                                              16.18               p-Xylene (pX)                                                                             8.65  15.63                                                                              15.16                                                                              17.02                                                                              17.33                                                                              18.08                                                                              18.33                                                                              18.56                                                                              18.16                                                                              18.68               m-Xylene (mX)                                                                             47.83 44.41                                                                              44.64                                                                              42.74                                                                              42.69                                                                              42.20                                                                              42.89                                                                              42.91                                                                              43.16                                                                              42.95               o-Xylene (oX)                                                                             23.66 20.79                                                                              20.98                                                                              20.64                                                                              20.59                                                                              20.29                                                                              19.89                                                                              19.72                                                                              20.04                                                                              19.90               C.sub.9.sup.+                                                                             .22   --   --   --   .72  .94  --   --   --   --                  Diethylbenzene                                                                            --    --   --   --   .39  .46  --   --   --   --                  Calculated Results                                                            ppH.sub.2, psia   144.5                                                                              136.7                                                                              141.3                                                                              146.5                                                                              141.6                                                                              142.1                                                                              145.3                                                                              142.9                                                                              148.9               H/HC              7.1  4.9  6.0  8.1  6.1  6.3  7.5  6.6  9.4                 t.sub.c, sec.     2.72 2.58 2.58 2.68 2.58 2.52 2.58 2.53 2.64                WHSV, hr.sup.-1   5.36 7.84 6.34 4.74 6.26 6.10 5.11 5.83 4.06                pX PATE, %        67.6 63.0 82.5 85.1 92.6 94.4 96.5 92.2 97.0                mX PATE, %        62.8 58.6 84.1 86.7 94.1 85.5 85.9 83.3 88.0                oX PATE, %        74.5 69.6 80.0 82.7 90.2 110.2                                                                              115.0                                                                              106.2                                                                              112.7               EB Conv., %       6.49 6.0  11.0 11.1 15.5 14.7 15.5 16.4 17.3                Time On Oil, hr   17.0 24.0 41.0 45.0 65.0 72.0 89.0 106.0                                                                              114.0               __________________________________________________________________________     .sup.1 FD = Feed                                                         

EXAMPLE XI

The air-calcined material was shown by X-ray diffraction analysis to bea mixture of crystalline chromosilicate and Cr₂ O₃, which mixture hasbeen shown to have catalytic activity to selectively isomerize mixedxylenes to a thermodynamic equilibrium mixture of mixed xylenes enrichedin para-xylene concentration. On a theoretical basis, one could arguethat this mixture of oxides could be made by impregnating an AMS-1-typesilica sieve with suitable chromia salts, which after calcination wouldyield an elemental oxide mixture that would have the characteristics ofthe above mixture.

A chromium acetate solution was prepared by dissolving 11.7 gm ofchromium acetate in 17.0 gm of distilled H₂ O and 3.0 gm of acetic acid.After the solution was prepared, 3.8 gm of AMS-1 silica sieve, having anXRD pattern of the AMS-1 family, were uniformly impregnated with 2.3 gmof the above solution and 1.0 gm of additional water was added to themixture to attain the water pore volume of the sieve. The impregnatedmaterial was allowed to equilibrate for 1 hr and was then slowly driedto attain a uniform impregnation of chromium on the sieve. The partiallydried material was given further drying at 165° C. overnight in a Thelcoforced air drying oven. The dried and impregnated sieve was calcined for4 hr at 1,000° F. (538° C.) using the programmed calcination aspreviously described. The impregnated sieve (3.7 gm) was dispersed in22.9 gm of PHF-alumina hydrosol (10.7 wt.% solids). A 15-gm quantity ofdistilled H₂ O was added to the slurry. The total slurry was heated to190° F. (88° C.) and stirred for 1.5 hr. An 8-ml portion of a solutionprepared from 4 ml of distilled H₂ O and 4 ml of concentrated ammoniumhydroxide was added to the slurry to gel the slurry. The slurry wasdried at 165° C. overnight in the forced draft drying oven. The driedmaterial was calcined at 1,000° F. (538° C.) for 4 hr using thecalcination program as previously described. The calcined material wascrushed and sieved for 30 to 50 mesh and then program-calcined at 1,000°F. (538° C.) for 4 hr again. A 1-gm sample of the catalyst, identifiedhereinafter as Catalyst No. 6, was tested for xylene isomerization inthe same manner as described in Test No. 2. This test, identifiedhereinafter as Test No. 6, furnished results, which are shown in TableXII. From these results, it can be seen that the impregnation of Cr₂ O₃on the AMS-1 silica sieve yields a catalyst which has no useful xyleneisomerization activity.

EXAMPLE XII

A sample of Catalyst No. 5 was given another treatment in air but at900° F. (482° C.) for 4 hr to maximize the migration of chromia in thecatalyst. This recalcined catalyst, identified hereinafter as CatalystNo. 7, was tested in the same manner as the catalyst in Test No. 2 wastested. The results are shown in Table XIII and are the same as theresults for the catalyst of Test No. 6. Therefore, it can be concludedthat the catalyst prepared from the impregnation of Cr₂ O₃ in AMS-1silica sieve does not reproduce the xylene isomerization activity of theair-calcined material, as shown in Test No. 2.

                                      TABLE XII                                   __________________________________________________________________________    TEST RESULTS - TEST NO. 6                                                     CATALYST NO. 6                                                                            Cut No.                                                                       FD.sup.1                                                                            2    3    4    5    6    7    8    9    10                  __________________________________________________________________________    Temperature, °F.                                                                         600  640  680  720  760  800  840  840  880                   °C.      316  338  360  382  404  427  449  449  471                 Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                    --    --   --   --   --   --   --   --   --   --                  Benzene     --    --   --   --   --   --   --   --   --   --                  Toluene     .06   .07  --   .07  .06  .06  .07  .09  .07  .11                 Ethylbenzene (EB)                                                                         19.12 19.06                                                                              19.10                                                                              19.06                                                                              19.10                                                                              19.09                                                                              18.82                                                                              18.98                                                                              19.07                                                                              19.09               p-Xylene (pX)                                                                             9.05  9.09 9.05 9.02 9.10 9.08 9.15 9.12 9.22 9.28                m-Xylene (mX)                                                                             48.25 48.20                                                                              48.28                                                                              48.24                                                                              48.22                                                                              48.25                                                                              48.14                                                                              48.20                                                                              48.13                                                                              48.05               o-Xylene (oX)                                                                             23.52 23.58                                                                              23.58                                                                              23.61                                                                              23.52                                                                              23.53                                                                              23.81                                                                              23.62                                                                              23.51                                                                              23.43               C.sub.9.sup.+                                                                             --    --   --   --   --   --   --   --   --   --                  Diethylbenzene                                                                            --    --   --   --   --   --   --   --   --   --                  __________________________________________________________________________     .sup.1 FD = Feed                                                         

                  TABLE XIII                                                      ______________________________________                                        TEST RESULTS - TEST NO. 7                                                     CATALYST NO. 7                                                                Cut No.        FD.sup.1                                                                             1      2    3    4    5                                 ______________________________________                                        Temperature, °F.                                                                             600    720  720  720  800                                °C.           316    382  382  382  427                               Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                       --     --     --   --   --   --                                Benzene        --     --     --   --   --   --                                Toluene        .06    --     .08  .05  .07  .06                               Ethylbenzene (EB)                                                                            19.12  19.16  19.13                                                                              19.11                                                                              19.09                                                                              19.12                             p-Xylene (pX)  9.05   9.14   9.05 9.04 9.04 9.08                              m-Xylene (mX)  48.25  48.20  48.25                                                                              48.27                                                                              48.27                                                                              48.25                             o-Xylene (oX)  23.52  23.50  23.49                                                                              23.52                                                                              23.53                                                                              23.49                             C.sub.9.sup.+  --     --     --   --   --   --                                Diethylbenzene --     --     --   --   --   --                                ______________________________________                                         .sup.1 FD = Feed                                                         

EXAMPLE XIII

This example is provided to show that the results obtained from the useof an air-calcined chromosilicate, such as Sample No. 7, to isomerize axylene feed cannot be reproduced by use of a material that is preparedby the impregnation of a silica gel with Cr₂ O₃.

Grade 59 silica gel, obtained from the Davison Chemical Division of W.R. Grace & Company, was crushed and sieved to provide a 30-to-50-meshmaterial. A 15.2-gm portion of this sieved material was uniformlyimpregnated with 9.2 gm of the chromium acetate solution that had beenprepared in Example XI and 10.0 gm of distilled H₂ O were added toachieve a pore-volume filling of solution. The impregnated material wasallowed to equilibrate for 1.5 hr and then carefully dried in aforced-draft oven at 165° C. with further drying at 165° C. overnight.The dried and impregnated silica was given a programmed calcination at1,000° F. (538° C.) for 4 hr, as described hereinbefore. (Thisimpregnated material was calcined with the Catalyst No. 6 during thesecond programmed calcination of Example XI.) One gram of thischromia-on-Grade 59 silica was tested for xylene isomerization in thesame manner as used in Example IX. This chromia-on-Grade 59 silica gelis identified hereinafter as Catalyst No. 8 and the test as Test No. 8,the results of which are presented in Table XIV. This catalyst was foundto be inactive for xylene isomerization.

EXAMPLE XIV

Using the same technique that was employed in Example X, 5 gm ofCatalyst No. 6 were given another programmed calcination, but at atemperature of 900° F. (482° C.), to maximize any migration of thechromia. The resultant material is identified hereinafter as CatalystNo. 9.

A 1-gm portion of Catalyst No. 9 was tested for xylene isomerization inTest No. 9 in the same manner that was employed in Example IX. Theresults of this Test No. 9 are presented in Table XV and show thatCatalyst No. 9 was relatively inert for xylene isomerization.

As shown in the previous examples, the crystalline chromosilicatematerial that is prepared by crystallization and subsequent drying at amild temperature, e.g., 165° C., does provide the X-ray diffractionpattern specified hereinabove. This material has been designated asComposition A. Upon calcination of Composition A in air at a temperatureof about 1,000° F. (538° C.) for a period of time of about 4 hr,Composition B forms. Composition B has been shown to be a mixture of anoxide of chromium, i.e., Cr₂ O₃, and a molecular sieve material,presumably a chromosilicate sieve. This mixture provides an X-raydiffraction pattern that is similar to that provided by Composition A.Upon increasing the amount of chromium in the crystallization mixture ofreactants, as demonstrated hereinbefore by larger chromium factors,various peaks in the X-ray diffraction pattern that correspond to thoseproduced by chromia are enlarged. This Composition B, when prepared intoa catalyst, has shown activity for the conversion of hydrocarbons, e.g.,the isomerization of xylenes. It has been found that such catalyticactivity of Composition B cannot be duplicated by impregnation of anAMS-1-type silica sieve with chromia, Cr₂ O₃. Furthermore, the silica ofComposition B is not the same as the silica of the AMS-1-type molecularsieve.

                                      TABLE XIV                                   __________________________________________________________________________    TEST RESULTS - TEST No. 8                                                     CATALYST NO. 8                                                                Cut No.      FD.sup.1                                                                          1   2   3   4   5   6   7   8   9   10                       __________________________________________________________________________    Temperature, °F.                                                                        600 600 640 680 720 760 800 840 840 880                       °C.      316 316 338 360 382 404 427 449 449 471                      Product Analysis, wt. %                                                       Paraffins & Napthenes                                                                      --  --  --  --  --  --  --  --  --  --  --                       Benzene      --  .18 --  --  --  --  --  --  --  --  --                       Toluene      .06 .10 .08 .05 .07 .07 .06 .09 .07 .08 .09                      Ethylbenzene (EB)                                                                          19.12                                                                             18.70                                                                             19.05                                                                             19.12                                                                             19.04                                                                             19.18                                                                             19.11                                                                             19.06                                                                             18.90                                                                             19.12                                                                             19.06                    p-Xylene (pX)                                                                              9.05                                                                              10.16                                                                             9.06                                                                              9.06                                                                              9.00                                                                              9.10                                                                              9.02                                                                              9.04                                                                              9.03                                                                              9.07                                                                              9.02                     m-Xylene (mX)                                                                              48.25                                                                             47.60                                                                             48.29                                                                             48.22                                                                             48.29                                                                             48.15                                                                             48.26                                                                             48.29                                                                             48.14                                                                             48.26                                                                             48.27                    o-Xylene (oX)                                                                              23.52                                                                             23.25                                                                             23.52                                                                             23.56                                                                             23.60                                                                             23.56                                                                             23.54                                                                             23.51                                                                             23.86                                                                             23.48                                                                             23.57                    C.sub.9.sup.+                                                                              --  --  --  --  --  --  --  --  --  --  --                       Diethylbenzene                                                                             --  --  --  --  --  --  --  --  --  --  --                       __________________________________________________________________________     .sup.1 FD = Feed                                                         

                  TABLE XV                                                        ______________________________________                                        TEST RESULTS - TEST NO. 9                                                     CATALYST NO. 9                                                                Cut No.        FD.sup.1                                                                             1      2    3    4    5                                 ______________________________________                                        Temperature, °F.                                                                             600    720  720  720  800                                °C.           316    382  382  382  427                               Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                       --     --     --   --   --   --                                Benzene        --     --     --   --   --   --                                Toluene        .06    .08    .07  .08  .06  .05                               Ethylbenzene (EB)                                                                            19.12  19.14  19.09                                                                              19.11                                                                              19.10                                                                              19.06                             p-Xylene (pX)  9.05   9.07   9.01 9.02 9.03 9.12                              m-Xylene (mX)  48.25  48.15  48.24                                                                              48.23                                                                              48.25                                                                              48.18                             o-Xylene (oX)  23.52  23.52  23.55                                                                              23.57                                                                              23.56                                                                              23.60                             C.sub.9.sup.+  --     --     --   --   --   --                                Diethylbenzene --     --     --   --   --   --                                ______________________________________                                         .sup.1 FD = Feed                                                         

EXAMPLE XV

In this example, a crystalline chromosilicate was prepared, during thepreparation of which a treatment in hydrogen was employed.

First, 9.6 gm of Cr₂ (SO₄)₃.xH₂ O were dissolved in 400 gm of distilledH₂ O. To this solution were added 5.2 gm of NaOH. After the NaOH wasdissolved in the solution, 62.4 gm of tetra-n-propylammonium bromide(TPABr) were added to that solution and dissolved therein. Then 76.4 gmof Ludox HS-40 were added to the solution with vigorous stirring. Aslurry resulted and was placed into a crystallization vessel andcrystallized at a temperature of 165° C. for 7 days. The contents werethen removed from the crystallizer and the solid material was filteredfrom the solution and was washed with at least twice the volume of H₂ Othat had been used in the original crystallization solution. The solidwas subsequently filter dried and then placed in a forced-air dryingoven for drying overnight at a temperature of about 165° C.

The dried solid was charged to a stainless steel tube reactor which wasfixed in a vertical position in a Lundberg 3-Zone furnace. Air waspurged from the system overnight with a flow of helium of approximately1.5 standard cubic feet per hour (SCFH) while the Eurotherm furnacecontrols were set at a temperature of 200° F. (93° C.). The helium flowwas stopped and a flow of hydrogen of about 3 SCFH was initiated. Thetemperature setting for the furnace was increased 50° F. every 15minutes until a temperature of 1,000° F. (538° C.) was attained. Thetemperature was then held at 1,000° F. (538° C.) for 4 hr, after whichthe temperature controls were set at 200° F. (93° C.) and the furnace,the reactor, and the contents of the reactor were allowed to cool to200° F. (93° C.) overnight. When the temperature settings were changedto 200° F. (93° C.), the hydrogen flow was stopped and a flow of heliumof about 1.5 SCFH was started, in order to purge the hydrogen from thesystem overnight. The solid material was cooled, purged with helium, andremoved from the tube furnace. This solid material was analyzed by X-raydiffraction and found to be AMS-1Cr crystalline chromosilicate. No freeCr₂ O₃ was found to be present. This material, identified as Sample No.14, is hydrogen-treated crystalline chromosilicate and represents anembodiment of Composition C, which has been discussed hereinabove.

Approximately 1 gm of Sample No. 14 was calcined in air at a temperatureof 1,000° F. (538° C.) for 4 hr. X-ray diffraction analysis of thiscalcined material showed that it comprised crystalline chromosilicateand approximately 10 wt.% Cr₂ O₃.

EXAMPLE XVI

This example is presented to demonstrate that the AMS-1Cr crystallinechromosilicate that has been hydrogen treated at a high temperature canbe cation-exchanged with calcium ions.

A 5-gm portion of Sample No. 14 obtained from Example XV wascation-exchanged 5 times with calcium acetate solutions. Each solutionhad been prepared by dissolving 10 gm of calcium acetate in 150 ml ofdistilled H₂ O. In addition, the second exchange was performed with theexchange solution after its initial pH had been adjusted to a value of3.0 by the addition of dilute nitric acid. Each exchange was carried outfor a period of 1.5 hr at a temperature of 190° F. (88° C.). Theoriginal Sample No. 14 contained 5.20 wt.% chromium and 0.55 wt.%sodium, on an ignited basis. The exchanged material contained, on anignited basis, 3.68 wt.% chromium, 1.45 wt.% calcium, and 0.051 wt.%sodium. On the basis of 100 gm, the exchanged AMS-1Cr chromosilicatewould contain 3.68/52.01 moles of chromium, i.e., 0.708 moles ofchromium; (1.45)(2)/40.08 equivalents of calcium, i.e., 0.723equivalents of calcium; and 0.051/22.997 equivalents of sodium, i.e.,0.0021 equivalents of sodium. Hence, there are 0.0744 equivalents ofexchangeable cation. Consequently, the equivalents of exchangeablecation are within 5% of being equal to the moles of tetrahedralchromium. This furnishes a necessary prerequisite for the chromium to beconsidered within the framework of the molecular sieve material. Theacid treatment of the second exchange leached out some chromium from thesieve framework.

EXAMPLE XVII

In this example, a catalyst containing a nickel-exchanged form of thehydrogen-treated AMS-1Cr crystalline chromosilicate, Sample No. 14, wasprepared and tested for its ability to isomerize a xylene feed.

A 15-gm portion of Sample No. 14 was cation-exchanged with a solutionthat had been prepared by dissolving 15 gm of ammonium acetate in 150 mlof distilled H₂ O. The exchange was carried out for 1.5 hr at atemperature of 95° C. The exchanged sieve was filtered from the exchangesolution and washed with approximately 200 ml of distilled H₂ O. Thesieve was allowed to air dry on the filter overnight. This exchangeprocedure was repeated four times to give a total of five ammoniumacetate exchanges. The last exchange was followed with a one-literdistilled-water wash. The washed material was filtered dried and thentransferred to the forced-draft oven to dry at a temperature of 165° C.overnight.

The dried ammonium form of the crystalline chromosilicate wastransferred to a 3/4-inch stainless steel tube reactor. The air waspurged from the system with a small flow of helium of approximately 1.5SCFH overnight at a temperature of 300° F. (149° C.). The helium flowwas stopped and a hydrogen flow of 3 SCFH was initiated. The temperaturewas increased at the rate of 100° F. every 30 min until a temperature of1,000° F. (538° C.) was reached. This temperature was maintained for 4hr. The hydrogen flow, after the 4 hr, was replaced with a helium flowof about 1.5 SCFH. The temperature controls of the furnace were set to atemperature of 200° F. (93° C.). The furnace cooled via its heat-lossrate which required about 6 hr.

The hydrogen-treated hydrogen form of AMS-1Cr crystalline chromosilicatewas then cation-exchanged with 150 ml of a 5% solution of Ni(NO₃)₂.6H₂ Ofor 1.5 hr at a temperature of 190° F. (88° C.). The sieve was filteredfrom the exchange solution, washed with 100 ml of distilled H₂ O, andfilter dried. The sieve was then transferred to a forced-draft dryingoven to dry overnight at a temperature of 165° C.

The 13.6 gm of dried, nickel-exchanged crystalline chromosilicate wasuniformly dispersed in 84.2 gm of PHF-alumina hydrosol containing 8.7wt.% solids, obtained from the American Cyanamid Company. A 20-gmquantity of distilled H₂ O was added to the sieve to aid dispersion inthe hydrosol. The hydrosol plus dispersed sieve was gelled with theaddition of 20 ml of a 1-to-1 solution of concentrated ammoniumhydroxide in distilled water. The dried sieve was charged to the tubereactor for another hydrogen treatment at a temperature of 1,000° F.(538° C.) for 4 hr using the previously-described procedure. Thehydrogen-treated catalyst was crushed and sized to obtain a30-to-50-mesh material. The 30-to-50 mesh material was charged to thetop portion of the tube reactor for a final activation with a hydrogentreatment at a temperature of 1,000° F. (538° C.) for 4 hr, aspreviously described, with the hydrogen flowing downward in the verticalreactor. This hydrogen-treated catalyst is identified hereinafter asCatalyst No. 10 and was tested for its ability to isomerize a xylenefeed.

A 1-gm portion of Catalyst No. 10 was tested in the same manner asdescribed hereinabove in Example IX. The results of this test,identified hereinafter as Test No. 10, are presented hereinafter inTable XVI. These results indicate that this Catalyst No. 10, containinga nickel-exchanged molecular sieve that had been identified anddescribed as AMS-1Cr crystalline chromosilicate, has selective catalyticactivity for xylene isomerization with an appreciable conversion ofethylbenzene to benzene.

                                      TABLE XVI                                   __________________________________________________________________________    TEST RESULTS - TEST NO. 10                                                    CATALYST NO. 10                                                               Cut No.     FD.sup.1                                                                         8   9   10  11  12  13  14  15  16  17  18  19                 __________________________________________________________________________    Temperature, °F.                                                                      800 840 840 840 840 840 840 840 840 880 880 880                 °C.    427 449 449 449 449 449 449 449 449 471 471 471                Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                    -- .05 .04 .04 .09     --  --  --  --  .04 --  .04                Benzene     -- .61 .96 1.01                                                                              1.06                                                                              .96 1.05                                                                              1.09                                                                              1.03                                                                              1.11                                                                              1.75                                                                              1.78                                                                              1.80               Toluene     .06                                                                              --  .18 .19 .21 .20 .20 .20 .18 .20 .33 .30 .33                Ethylbenzene (EB)                                                                         19.12                                                                            18.28                                                                             17.77                                                                             17.69                                                                             17.46                                                                             17.70                                                                             17.54                                                                             17.48                                                                             17.59                                                                             17.57                                                                             16.48                                                                             17.49                                                                             16.52              p-Xylene (pX)                                                                             9.05                                                                             14.46                                                                             16.11                                                                             16.30                                                                             16.52                                                                             15.91                                                                             16.51                                                                             16.54                                                                             16.33                                                                             16.56                                                                             17.87                                                                             17.65                                                                             17.74              m-Xylene (mX)                                                                             48.25                                                                            44.83                                                                             43.68                                                                             43.61                                                                             43.55                                                                             43.92                                                                             43.53                                                                             43.49                                                                             42.68                                                                             43.57                                                                             42.96                                                                             43.03                                                                             42.87              o-Xylene (oX)                                                                             23.52                                                                            21.79                                                                             21.27                                                                             21.16                                                                             21.11                                                                             21.30                                                                             21.16                                                                             21.21                                                                             20.82                                                                             20.99                                                                             20.57                                                                             20.75                                                                             20.70              C.sub.9.sup.+                                                                             -- --  --  --  --  --  --  --  --  --  --  --  --                 Diethylbenzene                                                                            -- --  --  --  --  --  --  --  --  --  --  --  --                 Calculated Results                                                            ppH.sub.2, psia                                                                              142.0                                                                             142.7                                                                             142.7                                                                             142.3                                                                             140.2                                                                             144.8                                                                             142.0                                                                             143.1                                                                             141.6                                                                             143.6                                                                             141.8                                                                             142.3              H/HC           6.1 6:5 6.5 6.3 5.7 7.3 6.3 6.6 6.1 6.8 6.2 6.3                t.sub.c, sec.  2.67                                                                              2.60                                                                              2.61                                                                              2.60                                                                              2.56                                                                              2.64                                                                              2.59                                                                              2.61                                                                              2.59                                                                              2.54                                                                              2.51                                                                              2.52               WHSV, hr.sup.-1                                                                              6.13                                                                              5.91                                                                              5.90                                                                              6.03                                                                              6.70                                                                              5.26                                                                              6.11                                                                              5.79                                                                              6.23                                                                              5.61                                                                              6.19                                                                              6.04               pX PATE, %     54.2                                                                              71.3                                                                              73.2                                                                              75.2                                                                              69.1                                                                              75.1                                                                              75.3                                                                              76.1                                                                              75.7                                                                              88.9                                                                              86.8                                                                              87.8               mX PATE, %     58.2                                                                              74.7                                                                              75.9                                                                              77.8                                                                              71.5                                                                              78.3                                                                              79.3                                                                              80.2                                                                              77.0                                                                              86.8                                                                              86.0                                                                              87.5               oX PATE, %     47.6                                                                              65.1                                                                              68.3                                                                              70.5                                                                              64.8                                                                              69.3                                                                              68.2                                                                              68.8                                                                              73.4                                                                              93.1                                                                              87.9                                                                              88.5               EB Conv., %    4.4 7.1 7.5 8.7 7.4 8.3 8.6 8.0 8.1 13.8                                                                              13.8                                                                              13.6               Time On Oil, hr                                                                              96  113 120 185 192 208 215 232 239 256 263 280                __________________________________________________________________________     .sup.1 FD = Feed                                                         

EXAMPLE XVIII

In this example, a catalyst containing a nickel-exchanged form of thehydrogen-treated crystalline chromosilicate and having been impregnatedwith a nickel nitrate solution was prepared and tested for its abilityto isomerize a xylene feed.

A 2-gm portion of Catalyst No. 10 in the form of 30-to-50-mesh materialwas impregnated with 4 gm of a 5% solution of Ni(NO₃)₂.6H₂ O indistilled water. The impregnated material was carefully dried in aforced-draft drying oven with frequent agitation at a temperature of165° C. for 1 hr and then dried for 4 additional hours at a temperatureof 165° C.

The dried impregnated catalyst was transferred to the lower portion ofthe tube reactor that was used to hydrogen treat the 30-to-50-meshmaterial in Example XVII. These two materials were placed in the tube atthe same time and in such a way as to minimize, if not eliminate,contamination of the original catalyst with the nitrogen oxides producedfrom the thermally-decomposing nitrate of the impregnated catalyst.Consequently, the placing of the original catalyst above the impregnatedcatalyst resulted in the flowing hydrogen passing through the originalcatalyst first. The hydrogen-treated, impregnated material ishereinafter identified as Catalyst No. 11. It was tested for its abilityto isomerize a xylene feed and was used in the form of a 30-to-50-meshmaterial.

A 1-gm portion of Catalyst No. 11 was tested in the same manner asdescribed hereinabove in Example IX. The results of this test,identified hereinafter as Test No. 11, are presented hereinafter inTable XVII.

A comparison of the results obtained from Test No. 11 with thoseobtained from Test No. 10 shows that the nickel-impregnated catalyst,Catalyst No. 11, has an isomerization activity that is significantlyhigher than that provided by the non-impregnated catalyst, Catalyst No.10. This enhanced activity can be attributed to the hydrogenationactivity of the impregnated nickel, which minimizes the formation ofcoke on the alumina matrix material. Such minimal coke production allowsincreased isomerization to occur on a metal-scavenged alumina surface.It is contemplated that other hydrogenation-dehydrogenation metals oroxides of metals, such as tungsten, molybdenum, cobalt, and the like,will promote the catalytic activity by maintaining a relativelycoke-free alumina surface.

The hydrogen-treated AMS-1Cr crystalline chromosilicate provides theX-ray diffraction pattern specified herein and presented in Example XXand has suitable catalytic activity for the conversion of hydrocarbons,e.g., the isomerization of xylenes. Such material has been identifiedhereinabove as Composition C. Composition C is a crystalline molecularsieve that is designated AMS-1Cr crystalline chromosilicate because: (1)ion-exchange dictates that chromium has replaced aluminum of typicalcrystalline aluminosilicates; (2) no Cr₂ O₃ was detected in the sievethat has been treated with hydrogen at elevated temperatures; and (3) a3-fold increase in chromium concentration in the chromosilicate sieveprovides a pronounced shoulder on the 3.85 A reflection. Composition Ccan be converted to Composition B by a calcination in air to yield acrystalline chromosilicate and a chromia phase. Composition C, as anAMS-1Cr crystalline chromosilicate molecular sieve, has an acidiccharacter in the hydrogen form which catalyzes the isomerization ofxylenes. In addition, the activity for the isomerization of xylenes isenhanced by the impregnation of the chromosilicate with nickel oranother hydrogenation-dehydrogenation metal.

                                      TABLE XVII                                  __________________________________________________________________________    TEST RESULTS - TEST NO. 11                                                    CATALYST NO. 11                                                               __________________________________________________________________________    Cut No.      FD.sup.1                                                                          1   3   4   5   6   7   9   10  11                           __________________________________________________________________________    Temperature, °F.                                                                        600 640 680 720 760 800 800 800 800                           °C.      316 338 360 382 404 427 427 427 427                          Product Analysis, wt. %                                                       Paraffins & Naphthenes   --  .03 --  --  --  --  --                           Benzene      --  .08 .09 .20 .33 .53 1.00                                                                              .93 .90 .81                          Toluene      .06 .11 .09 .10 .11 .13 .20 .19 .20 .15                          Ethylbenzene (EB)                                                                          19.12                                                                             19.07                                                                             18.96                                                                             18.93                                                                             18.71                                                                             18.34                                                                             17.69                                                                             17.94                                                                             17.87                                                                             18.09                        p-Xylene (pX)                                                                              9.05                                                                              9.88                                                                              10.58                                                                             11.97                                                                             14.06                                                                             15.53                                                                             17.43                                                                             17.15                                                                             16.89                                                                             16.12                        m-Xylene (mX)                                                                              48.25                                                                             47.68                                                                             47.25                                                                             46.26                                                                             44.91                                                                             43.99                                                                             42.98                                                                             43.16                                                                             43.25                                                                             43.70                        o-Xylene (oX)                                                                              23.52                                                                             23.18                                                                             23.03                                                                             22.55                                                                             21.86                                                                             21.48                                                                             20.70                                                                             20.63                                                                             20.88                                                                             21.13                        C.sub.9.sup.+                                                                              --  --  --  --  --  --   -- --  --  --                           Diethylbenzene                                                                             --  --  --  --  --  --  --  --  --  --                           Calculated Results                                                            ppH.sub.2, psia  143.0                                                                             144.5                                                                             145.2                                                                             147.3                                                                             148.2                                                                             144.5                                                                             145.5                                                                             142.0                                                                             128.9                        H/HC             6.6 7.2 7.5 8.5 9.0 7.2 7.6 6.2 3.6                          t.sub.c, sec.    3.20                                                                              3.12                                                                              3.02                                                                              2.96                                                                              2.88                                                                              2.72                                                                              2.74                                                                              2.67                                                                              2.43                         WHSV, hr.sup.-1  5.80                                                                              5.34                                                                              5.13                                                                              4.51                                                                              4.26                                                                              5.34                                                                              5.01                                                                              6.13                                                                              10.61                        pX PATE, %       8.24                                                                              15.0                                                                              29.0                                                                              50.0                                                                              64.7                                                                              84.1                                                                              81.6                                                                              78.8                                                                              71.2                         mX PATE, %       10.23                                                                             19.2                                                                              35.4                                                                              58.2                                                                              73.4                                                                              88.6                                                                              84.2                                                                              83.5                                                                              75.5                         oX PATE, %       6.22                                                                              10.4                                                                              21.13                                                                             38.9                                                                              51.9                                                                              76.5                                                                              77.2                                                                              71.2                                                                              64.1                         EB Conv., %      .26 0.84                                                                              .99 2.1 4.1 7.5 6.2 6.5 5.4                          Time On Oil, hr  17  41  48  65  72.25                                                                             89.0                                                                              113.0                                                                             120.0                                                                             185.0                        __________________________________________________________________________    Cut No.      FD.sup.1                                                                              12  13  14  15  16  17  18  19                           __________________________________________________________________________    Temperature, °F.                                                                            800 840 840 840 840 880 880 880                                 °C.    427 449 449 449 449 471 471 471                          Product Analysis, wt. %                                                       Paraffins & Naphthenes                                                                             --  .05 .05 .03 .02 .01 .01 .01                          Benzene      --      .73 1.35                                                                              1.45                                                                              1.30                                                                              1.17                                                                              1.50                                                                              1.73                                                                              1.78                         Toluene      .06     .14 .22 .26 .26 .23 .35 .36 .37                          Ethylbenzene (EB)                                                                          19.12   18.07                                                                             17.23                                                                             17.07                                                                             16.68                                                                             16.90                                                                             15.83                                                                             15.73                                                                             15.86                        p-Xylene (pX)                                                                              9.05    15.65                                                                             17.63                                                                             17.77                                                                             17.89                                                                             17.72                                                                             18.57                                                                             18.53                                                                             18.51                        m-Xylene (mX)                                                                              48.25   44.03                                                                             42.90                                                                             42.87                                                                             42.70                                                                             42.85                                                                             42.67                                                                             42.54                                                                             42.50                        o-Xylene (oX)                                                                              23.52   21.39                                                                             20.62                                                                             20.53                                                                             20.51                                                                             20.57                                                                             20.36                                                                             20.32                                                                             20.18                        C.sub.9.sup.+                                                                              --      --  --  --  .65 .54 .76 .78 .78                          Diethylbenzene                                                                             --      --  --  --  .41 .34 .36 .38 .36                          Calculated Results                                                            ppH.sub.2, psia      138.6                                                                             149.0                                                                             145.6                                                                             142.2                                                                             140.2                                                                             143.6                                                                             142.7                                                                             143.8                        H/HC                 5.3 9.5 7.6 6.3 5.7 6.8 6.5 6.9                          t.sub.c, sec.        2.61                                                                              2.72                                                                              2.66                                                                              2.60                                                                              2.56                                                                              2.54                                                                              2.53                                                                              2.55                         WHSV, hr.sup.-1      7.22                                                                              4.03                                                                              5.01                                                                              6.05                                                                              6.69                                                                              5.62                                                                              5.91                                                                              5.55                         pX PATE, %           66.2                                                                              86.5                                                                              87.9                                                                              89.3                                                                              87.4                                                                              95.2                                                                              95.6                                                                              95.7                         mX PATE, %           71.2                                                                              87.9                                                                              88.5                                                                              90.6                                                                              88.6                                                                              92.5                                                                              93.2                                                                              91.5                         oX PATE, %           58.1                                                                              84.1                                                                              86.7                                                                              86.8                                                                              85.3                                                                              100.3                                                                             100.5                                                                             103.8                        EB Conv., %          5.5 9.9 10.7                                                                              12.8                                                                              11.6                                                                              17.2                                                                              17.7                                                                              17.2                         Time On Oil, hr      190.0                                                                             206.0                                                                             213.0                                                                             230.0                                                                             237.0                                                                             254.0                                                                             261.0                                                                             278.0                        __________________________________________________________________________

EXAMPLE XIX

The X-ray diffraction pattern for the Sample No. 11 AMS-1Crchromosilicate of Example VIII was found to be:

                  TABLE XVIII                                                     ______________________________________                                        Interplanar Spacings      Assigned                                            d, A              I/I.sub.o                                                                             Strength                                            ______________________________________                                        11.14 ± 0.2    33      M                                                   9.89 ± 0.2     100     VS                                                  6.71 ± 0.2     4       VW                                                  6.35 ± 0.1     6       VW                                                  5.99 ± 0.1     10      W                                                   5.71 ± 0.1     7       VW                                                  5.58 ± 0.1     7       VW                                                  5.34 ± 0.1     3       VW                                                  4.97 ± 0.1     20      M                                                   4.61 ± 0.08    3       VW                                                  4.36 ± 0.08    5       VW                                                  4.26 ± 0.08    8       VW                                                  4.07 ± 0.08    6       VW                                                  4.01 ± 0.08    3       VW                                                  3.85 ± 0.07    47      MS                                                  3.81 ± 0.07    37      M                                                   3.72 ± 0.05    26      M                                                   3.63 ± 0.05    32      M                                                   3.57 ± 0.05    3       VW                                                  3.49 ± 0.05    3       VW                                                  3.43 ± 0.05    5       VW                                                  3.35 ± 0.05    7       VW                                                  3.31 ± 0.05    13      W                                                   3.25 ± 0.05    2       VW                                                  3.17 ± 0.05    3       VW                                                  3.05 ± 0.03    4       VW                                                  3.04 ± 0.03    4       VW                                                  2.99 ± 0.02    10      W                                                   2.95 ± 0.02    8       VW                                                  2.90 ± 0.02    3       VW                                                  2.74 ± 0.02    5       VW                                                  2.67 ± 0.02    35      M                                                   2.48 ± 0.02    38      M                                                   2.43 ± 0.02    3       VW                                                  2.27 ± 0.02    2       VW                                                  2.20 ± 0.02    2       VW                                                  2.17 ± 0.02    13      W                                                   2.04 ± 0.02    3       VW                                                  2.01 ± 0.02    6       VW                                                  1.99 ± 0.02    16      W                                                   1.82 ± 0.02    13      W                                                   1.76 ± 0.02    4       VW                                                  1.67 ± 0.02    32      M                                                   ______________________________________                                    

Please note that this has a higher chromium concentration than thesample which provided the X-ray diffraction pattern exhibited in Table Ihereinabove. The increased amount of chromium that was on the sieveframework caused a shift in some d spacings, for example, 11.04 wasshifted to 11.14 and 10.04 to 9.89, and a change in some relativeintensities, for example, the corresponding relative intensities changedfrom 100 to 33 and 68 to 100, respectively.

The importance of the 2.67 and 2.48 interplanar spacings is in directproportion to the chromium concentration in the sieve framework prior tothe airtreatment.

The stronger peaks for this air-treated AMS-1Cr crystallinechromosilicate are presented hereinbelow in Table XIX.

                  TABLE XIX                                                       ______________________________________                                        Interplanar Spacings      Assigned                                            d, A              I/I.sub.o                                                                             Strength                                            ______________________________________                                        11.14 ± 0.2    33      M                                                   9.89 ± 0.02    100     VS                                                  3.85 ± 0.07    47      MS                                                  3.81 ± 0.07    37      M                                                   3.72 ± 0.05    26      M                                                   3.63 ± 0.05    32      M                                                   2.67 ± 0.02    35      M                                                   2.48 ± 0.02    38      M                                                   ______________________________________                                    

EXAMPLE XX

The x-ray diffraction pattern for the Sample No. 14 AMS-1Crchromosilicate of Example XV was found to be:

                  TABLE XX                                                        ______________________________________                                        Interplanar Spacings      Assigned                                            d, A              I/I.sub.o                                                                             Strength                                            ______________________________________                                        11.15 ± 0.2    11      W                                                   9.96 ± 0.2     100     VS                                                  9.03 ± 0.2     0.4     VW                                                  7.48 ± 0.2     0.6     VW                                                  7.09 ± 0.2     0.4     VW                                                  6.72 ± 0.2     0.6     VW                                                  6.36 ± 0.1     1.2     VW                                                  5.99 ± 0.1     6       VW                                                  5.71 ± 0.1     6       VW                                                  5.56 ± 0.1     2       VW                                                  5.36 ± 0.1     0.4     VW                                                  4.97 ± 0.1     17      W                                                   4.62 ± 0.08    0.7     VW                                                  4.47 ± 0.08    0.6     VW                                                  4.36 ± 0.08    0.6     VW                                                  4.26 ± 0.08    2       VW                                                  4.01 ± 0.08    2       VW                                                  3.85 ± 0.07    29      M                                                   3.82 ± 0.07    48      MS                                                  3.75 ± 0.05    23      M                                                   3.44 ± 0.05    2       VW                                                  3.35 ± 0.05    2       VW                                                  3.32 ± 0.05    9       VW                                                  3.25 ± 0.05    1       VW                                                  3.18 ± 0.05    0.4     VW                                                  3.06 ± 0.03    2       VW                                                  3.05 ± 0.03    2       VW                                                  2.99 ± 0.02    3       VW                                                  2.95 ± 0.02    2       VW                                                  2.86 ± 0.02    0.4     VW                                                  2.79 ± 0.02    1       VW                                                  2.73 ± 0.02    0.9     VW                                                  2.61 ± 0.02    1       VW                                                  2.56 ± 0.02    0.4     VW                                                  2.52 ± 0.02    1       VW                                                  2.49 ± 0.02    4       VW                                                  2.42 ± 0.02    0.9     VW                                                  2.39 ± 0.02    0.9     VW                                                  2.32 ± 0.02    0.4     VW                                                  2.20 ± 0.02    0.7     VW                                                  2.17 ± 0.02    0.5     VW                                                  2.01 ± 0.02    3       VW                                                  1.99 ± 0.02    12      W                                                   1.95 ± 0.02    0.9     VW                                                  1.91 ± 0.02    0.9     VW                                                  1.88 ± 0.02    0.5     VW                                                  1.86 ± 0.02    0.4     VW                                                  ______________________________________                                    

The stronger peaks for this hydrogen-treated AMS-1Cr crystallinechromosilicate are presented hereinbelow in Table XXI:

                  TABLE XXI                                                       ______________________________________                                        Interplanar Spacings      Assigned                                            d, A              I/I.sub.o                                                                             Strength                                            ______________________________________                                        11.15 ± 0.2    11      W                                                   9.96 ± 0.2     100     VS                                                  5.99 ± 0.1      6      VW                                                  5.71 ± 0.1      6      VW                                                  4.97 ± 0.1     17      W                                                   3.85 ± 0.07    29      M                                                   3.82 ± 0.07    48      MS                                                  3.75 ± 0.05    23      M                                                   3.32 ± 0.05     9      VW                                                  1.99 ± 0.02    12      W                                                   ______________________________________                                    

As shown hereinabove, a catalytically active material can be obtainedwhen the heat treatment is carried out in either a hydrogen atmosphereor an oxygen-containing atmosphere. Composition C will result ifhydrogen is employed; Composition B will result if an oxygen-containingatmosphere is used.

What is claimed is:
 1. A crystalline chromosilicate, whichchromosilicate comprises a molecular sieve material providing an X-raydiffraction pattern comprising the following X-ray diffraction lines andassigned strengths:

    ______________________________________                                        Interplanar Spacing  Assigned                                                 d, A                 Strength                                                 ______________________________________                                        11.04 ± 0.2       S                                                        10.04 ± 0.2       S                                                        3.80 ± 0.07       VS                                                       3.74 ± 0.05       M                                                        3.70 ± 0.05       S                                                        3.64 ± 0.05       MS                                                       ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2[WR.sub.2 O+(1-W)M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein R is an alkylammonium cation, M is at least one cation having avalence of n, Y is a value within the range of about 4 to about 500, Zis a value within the range of about 0 to about 160, and W is a valuethat is greater than or equal to 0 and less than or equal to
 1. 2. Thechromosilicate of claim 1, said chromosilicate having been prepared bythe method which comprises: (1) preparing a mixture containing an oxideof silicon, a compound of chromium, a hydroxide of an alkali metal or analkaline earth metal, an alkylammonium cation or a precursor of analkylammonium cation, and water; (2) maintaining said mixture atsuitable reaction conditions to effect formation of said chromosilicate,said reaction conditions comprising a temperature within the range ofabout 25° C. to about 300° C., a pressure of at least the vapor pressureof water at said temperature, and a reaction time that is sufficient toeffect crystallization to crystals of said chromosilicate; and (3)drying said crystals.
 3. The chromosilicate of claim 1, wherein saidcompound of chromium is Cr₂ (SO₄)₃.xH₂ O or Cr(C₂ H₃ O₂)₃.H₂ O.
 4. Thechromosilicate of claim 2, wherein said compound of chromium is Cr₂(SO₄)₃.xH₂ O or Cr(C₂ H₃ O₂)₃.H₂ O.
 5. The chromosilicate of claim 2,wherein said mixture that is prepared in step (1) of said method ofpreparation has ratios of the initial reactant concentrations in thefollowing ranges:

    ______________________________________                                        SiO.sub.2 /Cr.sub.2 O.sub.3                                                                       1-500                                                     R.sub. N.sup.+ /(R.sub.4 'N.sup.+ + Na.sup.+)                                                    0.1-1                                                      OH.sup.- /SiO.sub.2                                                                              0.1-10                                                     H.sub.2 O/OH.sup.-  10-500                                                    ______________________________________                                    

wherein R' is an alkyl group and Na⁺ represents sodium, any other alkalimetal, or an alkaline earth metal.
 6. The chromosilicate of claim 5,wherein said compound of chromium is Cr₂ (SO₄)₃.xH₂ O or Cr(C₂ H₃O₂)₃.H₂ O.
 7. A crystalline chromosilicate, which chromosilicatecomprises a molecular sieve material providing an X-ray diffractionpattern comprising the following X-ray diffraction lines and assignedstrengths:

    ______________________________________                                        Interplanar Spacing                                                                            Assigned                                                     d, A             Strength                                                     ______________________________________                                        11.15 ± 0.2   W                                                            9.96 ± 0.2    VS                                                           5.99 ± 0.1    VW                                                           5.71 ± 0.1    VW                                                           4.97 ± 0.1    W                                                            3.85 ± 0.07   M                                                            3.82 ± 0.07   MS                                                           3.75 ± 0.05   M                                                            3.32 ± 0.05   VW                                                           1.99 ± 0.02   W                                                            ______________________________________                                    

and having the following composition in terms of mole ratios of oxides:

    0.9±0.2M.sub.2/n O:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is an least one cation having a valence of n, Y is within therange of about 4 to about 5000, and Z is within the range of 0 to about160.
 8. The chromosilicate of claim 7, wherein Y is a value within therange of about 4 to about
 80. 9. The chromosilicate of claim 7, whereinZ is a value within the range of 0 to about
 40. 10. The chromosilicateof claim 7, wherein M is selected from the group consisting ofalkylammonium cations, ammonium cation, hydrogen cation, metal cations,and mixtures thereof.
 11. The chromosilicate of claim 7, saidchromosilicate having been prepared by the method which comprises: (1)preparing a mixture containing an oxide of silicon, a compound ofchromium, a hydroxide of an alkali metal or an alkaline earth metal, analkylammonium cation or a precursor of an alkylammonium cation, andwater; (2) maintaining said mixture at suitable reaction conditions toeffect formation of said chromosilicate, said reaction conditionscomprising a temperature within the range of about 25° C. to about 300°C., a pressure of at least the vapor pressure of water at saidtemperature, and a reaction time that is sufficient to effectcrystallization to crystals of said chromosilicate; (3) drying saidcrystals; and (4) activating said crystals of chromosilicate by heattreating said crystals at a temperature within the range of about 800°F. (427° C.) to about 1,700° F. (927° C.) in the presence of ahydrogen-containing atmosphere.
 12. The chromosilicate of claim 8,wherein Z is a value within the range of 0 to about
 40. 13. Thechromosilicate of claim 10, wherein M comprises nickel.
 14. Thechromosilicate of claim 11, wherein said mixture that is prepared instep (1) of said method of preparation has ratios of the initialreactant concentrations in the following ranges:

    ______________________________________                                        SiO.sub.2 /Cr.sub.2 O.sub.3                                                                       1-500                                                     R.sub. N.sup.+ /(R.sub.4 'N.sup.+ + Na.sup.+)                                                    0.1-1                                                      OH.sup.- /SiO.sub.2                                                                              0.1-10                                                     H.sub.2 O/OH.sup.-  10-500                                                    ______________________________________                                    

wherein R' is an alkyl group and Na⁺ represents sodium, any other alkalimetal, or an alkaline earth metal.
 15. The chromosilicate of claim 12,wherein M is selected from the group consisting of alkylammoniumcations, ammonium cation, hydrogen cation, metal cations, and mixturesthereof.
 16. The chromosilicate of claim 12, said chromosilicate havingbeen prepared by the method which comprises: (1) preparing a mixturecontaining an oxide of silicon, a compound of chromium, a hydroxide ofan alkali metal or an alkaline earth metal, an alkylammonium cation or aprecursor of an alkylammonium cation, and water; (2) maintaining saidmixture at suitable reaction conditions to effect formation of saidchromosilicate, said reaction conditions comprising a temperature withinthe range of about 25° C. to about 300° C., a pressure of at least thevapor pressure of water of said temperature, and a reaction time that issufficient to effect crystallization to crystals of said chromosilicate;(3) drying said crystals; and (4) activating said crystals ofchromosilicate by heat treating said crystals at a temperature withinthe range of about 800° F. (427° C.) to about 1,700° F. (927° C.) in thepresence of a hydrogen-containing atmosphere.
 17. The chromosilicate ofclaim 14, wherein said compound of chromium is Cr₂ (SO₄)₃.xH₂ O or Cr(C₂H₃ O₂)₃.H₂ O.
 18. The chromosilicate of claim 15, wherein M comprisesnickel.
 19. The chromosilicate of claim 16, wherein said mixture that isprepared in step (1) of said method of preparation has ratios of theinitial reactant concentration in the following ranges:

    ______________________________________                                        SiO.sub.2 /Cr.sub.2 O.sub.3                                                                       1-500                                                     R.sub. N.sup.+ /(R.sub.4 'N.sup.+ + Na.sup.+)                                                    0.1-1                                                      OH.sup.- /SiO.sub.2                                                                              0.1-10                                                     H.sub.2 O/OH.sup.-  10-500                                                    ______________________________________                                    

wherein R' is an alkyl group and Na⁺ represents sodium, any other alkalimetal, or an alkaline earth metal.
 20. The chromosilicate of claim 19,wherein said compound of chromium is Cr₂ (SO₄)₃.xH₂ O or Cr(C₂ H₃O₂)₃.H₂ O.
 21. A method for preparing a crystalline chromosilicate,which method comprises: (1) preparing a mixture containing an oxide ofsilicon, a compound of chromium, a hydroxide of an alkali metal or analkaline earth metal, an alkylammonium cation or a precursor of analkylammonium cation, and water; (2) maintaining said mixture atsuitable reaction conditions to effect formation of the chromosilicate,said reaction conditions comprising a reaction temperature within therange of about 25° C. to about 300° C., a pressure of at least the vaporpressure of water at the reaction temperature, and a reaction time thatis sufficient to effect crystallization to crystals of saidchromosilicate; and (3) drying said crystals.
 22. The method of claim21, wherein said mixture that has been prepared in step (1) of saidmethod has ratios of the initial reactant concentrations in thefollowing ranges:

    ______________________________________                                        SiO.sub.2 /Cr.sub.2 O.sub.3                                                                       1-500                                                     R.sub. N.sup.+ /(R.sub.4 'N.sup.+ + Na.sup.+)                                                    0.1-1                                                      OH.sup.- /SiO.sub.2                                                                              0.1-10                                                     H.sub.2 O/OH.sup.-  10-500                                                    ______________________________________                                    

wherein R' is an alkyl group and Na⁺ represents sodium, any other alkalimetal, or an alkaline earth metal.
 23. The method of claim 21, whichmethod comprises further activating said crystals of chromosilicate byheat treating said crystals at a temperature within the range of about800° F. (427° C.) to about 1,700° F. (927° C.) in the presence of ahydrogen-containing atmosphere.
 24. The method of claim 21, wherein saidcompound of chromium is Cr₂ (SO₄)₃.xH₂ O or Cr(C₂ H₃ O₂)₃.H₂ O.
 25. Themethod of claim 22, which method comprises further activating saidcrystals of chromosilicate by heat treating said crystals at atemperature within the range of about 800° F. (427° C.) to about 1,700°F. (927° C.) in the presence of a hydrogen-containing atmosphere. 26.The method of claim 22, wherein said compound of chromium is Cr₂(SO₄)₃.xH₂ O or Cr(C₂ H₃ O₂)₃.H₂ O.
 27. The method of claim 23, whereinsaid chromosilicate is cation exchanged with a catalytically activemetal to provide a chromosilicate containing cations of said metal;drying said chromosilicate containing cations of said metal; andactivating the dried chromosilicate containing cations of said metal byheat treating said chromosilicate containing cations of said metal inthe presence of a hydrogen-containing atmosphere at a temperature withinthe range of about 800° F. (427° C.) to about 1,700° F. (927° C.). 28.The method of claim 24, which method comprises further activating saidcrystals of chromosilicate by heat treating said crystals at atemperature within the range of about 800° F. (427° C.) to about 1,700°F. (927° C.) in the presence of a hydrogen-containing atmosphere. 29.The method of claim 25, wherein said chromosilicate is cation exchangedwith a catalytically active metal to provide a chromosilicate containingcations of said metal; drying said chromosilicate containing cations ofsaid metal; and activating the dried chromosilicate containing cationsof said metal by heat treating said chromosilicate containing cations ofsaid metal in the presence of a hydrogen-containing atmosphere at atemperature within the range of about 800° F. (427° C.) to about 1,700°F. (927° C.).
 30. The method of claim 26, which method comprises furtheractivating said crystals of chromosilicate by heat treating saidcrystals at a temperature within the range of about 800° F. (427° C.) toabout 1,700° F. (927° C.) in the presence of a hydrogen-containingatmosphere.
 31. The method of claim 27, wherein said metal is nickel.32. The method of claim 28, wherein said chromosilicate is cationexchanged with a catalytically active metal to provide a chromosilicatecontaining cations of said metal; drying said chromosilicate containingcations of said metal; and activating the dried chromosilicatecontaining cations of said metal by heat treating said chromosilicatecontaining cations of said metal in the presence of ahydrogen-containing atmosphere at a temperature within the range ofabout 800° F. (427° C.) to about 1,700° F. (927° C.).
 33. The method ofclaim 29, wherein said metal is nickel.
 34. The method of claim 30,wherein said chromosilicate is cation exchanged with a catalyticallyactive metal to provide a chromosilicate containing cations of saidmetal; drying said chromosilicate containing cations of said metal; andactivating the dried chromosilicate containing cations of said metal byheat treating said chromosilicate containing cations of said metal inthe presence of a hydrogen-containing atmosphere at a temperature withinthe range of about 800° F. (427° C.) to about 1,700° F. (927° C.). 35.The method of claim 32, wherein said metal is nickel.
 36. The method ofclaim 34, wherein said metal is nickel.
 37. A crystalline chromosilicatehaving a composition in terms of mole ratios of oxides as follows:

    0.9±0.2M.sub.2/n O: Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein M is at least one cation having a valence of n, Y is between 4and about 200 and Z is between 0 and about 160, said chromosilicatehaving the X-ray diffraction lines and assigned strengths substantiallyas described in Table II of the specification.
 38. The composition ofclaim 37 further characterized in that Y is a value in the range of fromabout 4 to about
 80. 39. The composition of claim 37 furthercharacterized in that M is selected from the group consisting ofalkylammonium, ammonium, hydrogen, metal cations, and mixtures thereof.40. The composition of claim 39 further characterized in that Mcomprises nickel.
 41. The composition of claim 37 further characterizedin that M comprises hydrogen, nickel, and an alkali metal.
 42. Thecomposition of claim 37 further characterized in that M compriseshydrogen and nickel.
 43. The composition of claim 37 furthercharacterized in that Y is in the range of from about 4 to about
 40. 44.The composition of claim 43 further characterized in that Z is in therange of from 0 to about
 40. 45. The composition of claim 37 furthercharacterized in that Z is in the range of from 0 to about
 40. 46. Thecomposition of claim 37 further characterized in that Y is about
 16. 47.The composition of claim 37 further characterized in that saidchromosilicate has X-ray diffraction lines and assigned strengthssubstantially as described in Table I of the specification.
 48. Thecomposition of claim 47 further characterized in that Y is between 4 andabout 80 and Z is between 0 and about
 40. 49. A crystallinechromosilicate having a composition in terms of oxides as follows:

    0.9±0.2 [WR.sub.2 O+(1-W)M.sub.2/n O]:Cr.sub.2 O.sub.3 :YSiO.sub.2 :ZH.sub.2 O,

wherein R is tetrapropylammonium, M is an alkali metal cation, W isgreater than 0 and less than or equal to 1, Y is between 4 and 200, Z isbetween 0 and about 160 and having the X-ray diffraction lines andassigned strengths substantially as described in Table III of thespecification.
 50. The chromosilicate of claim 49 further characterizedin that Y is in the range of from about 5 to about
 100. 51. Thecomposition formed by contacting the composition of claim 49 at atemperature in excess of about 500° F. (260° C.) with ahydrogen-containing atmosphere.